Hi Suwash, thank you for the reply.
I’m using WordPress v5.9. MySQL version 10.5 and PHP version 7.4. The strange thing is that it works fine on the site I’m transferring it from (same host, just other domain).
I’ve uninstalled and deleted the plugin in WordPress and cleared cache with LiteSpeed Cache before installing it again. The same error unfortunately remains… Do you have any more tips?