Hi,
this is not an error of the upgrade but a package that is missing in your host.
It is usually php-mbstring, we need to add an alert about it.
If you enable this module mbstring or install this package the error is gone and the plugin can use a better language detection.
I added php-mbstring and re-enabled the plugin, but it still brings the same issue. Is there another package that needs to be added?
You need to enable this module inside your php configuration.In cpanel or plesk usually there is a page with a checklist wher you can enable the various libreries/modules.
Before the version changing you probably had this already configured but with the switch you need to do it again.
It is litespeed so I don’t know how works, if require other changes to enable it.
Maybe is something that you can ask to your hosting provider.
Thanks for the quick support on this, it ended up resolving the issue. It just took some time to propagate on the server. Cheers!