I have FTP access to the files, so I can delete cache or upload files if needed. I can also change PHP back to 7.4 and access the site like before and change settings in admin panel.
In mid January my ISP will no longer support that version, so I am in a bit of a hurry...
The CMSMS version is 2.2.8.
Any help will be greatly appreciated

When I turn on PHP error messages, this list below is shown, but I don't understand what the messages mean, or what I have to do.
Deprecated: Constant FILTER_SANITIZE_STRING is deprecated in /home/1/f/(site name)/www/lib/include.php on line 61
Deprecated: Constant FILTER_SANITIZE_STRING is deprecated in /home/1/f/(site name)/www/lib/include.php on line 62
Deprecated: Return type of cms_config::offsetExists($key) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.cms_config.php on line 338
Deprecated: Return type of cms_config::offsetGet($key) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.cms_config.php on line 346
Deprecated: Return type of cms_config::offsetSet($key, $value) should either be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.cms_config.php on line 563
Deprecated: Return type of cms_config::offsetUnset($key) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.cms_config.php on line 576
Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /home/1/f/(site name)/www/lib/classes/class.moduleoperations.inc.php on line 395
Warning: "continue" targeting switch is equivalent to "break". Did you mean to use "continue 2"? in /home/1/f/(site name)/www/lib/classes/class.moduleoperations.inc.php on line 402
Deprecated: Optional parameter $returnid declared before required parameter $smarty is implicitly treated as a required parameter in /home/1/f/(site name)/www/lib/classes/class.CMSModule.php on line 1429
Deprecated: Optional parameter $value declared before required parameter $items is implicitly treated as a required parameter in /home/1/f/(site name)/www/lib/classes/class.CMSModule.php on line 2071
Deprecated: Optional parameter $itemid declared before required parameter $action is implicitly treated as a required parameter in /home/1/f/(site name)/www/lib/classes/class.CMSModule.php on line 2846
Deprecated: Creation of dynamic property Smarty_Internal_Extension_Handler::$assignGlobal is deprecated in /home/1/f/(site name)/www/lib/smarty/sysplugins/smarty_internal_extension_handler.php on line 132
Deprecated: Creation of dynamic property Smarty_Internal_Extension_Handler::$registerResource is deprecated in /home/1/f/(site name)/www/lib/smarty/sysplugins/smarty_internal_extension_handler.php on line 132
Deprecated: Creation of dynamic property Smarty_Internal_Extension_Handler::$registerDefaultPluginHandler is deprecated in /home/1/f/(site name)/www/lib/smarty/sysplugins/smarty_internal_extension_handler.php on line 132
Deprecated: Creation of dynamic property Smarty_Internal_Extension_Handler::$registerPlugin is deprecated in /home/1/f/(site name)/www/lib/smarty/sysplugins/smarty_internal_extension_handler.php on line 132
Deprecated: Creation of dynamic property CMSSmartySecurityPolicy::$smarty is deprecated in /home/1/f/(site name)/www/lib/smarty/sysplugins/smarty_security.php on line 260
Deprecated: trim(): Passing null to parameter #1 ($string) of type string is deprecated in /home/1/f/(site name)/www/lib/classes/class.FileTypeHelper.php on line 86
Deprecated: Return type of CmsRoute::OffsetExists($key) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.CmsRoute.php on line 147
Deprecated: Return type of CmsRoute::OffsetGet($key) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.CmsRoute.php on line 131
Deprecated: Return type of CmsRoute::OffsetSet($key, $value) should either be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.CmsRoute.php on line 139
Deprecated: Return type of CmsRoute::OffsetUnset($key) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/1/f/(site name)/www/lib/classes/class.CmsRoute.php on line 157
Deprecated: Optional parameter $value declared before required parameter $items is implicitly treated as a required parameter in /home/1/f/(site name)/www/lib/classes/internal/module_support/modform.inc.php on line 499
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$class is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 284
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$friendlyname_key is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 293
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$class is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 284
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$friendlyname_key is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 293
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$class is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 284
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$friendlyname_key is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 290
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$class is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 284
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$friendlyname_key is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 293
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$class is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 284
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$friendlyname_key is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 293
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$class is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 284
Deprecated: Creation of dynamic property CmsContentTypePlaceholder::$friendlyname_key is deprecated in /home/1/f/(site name)/www/lib/classes/class.contentoperations.inc.php on line 293
Fatal error: Array and string offset access syntax with curly braces is no longer supported in /home/1/f/(site name)/www/modules/Search/PorterStemmer.class.php on line 393