Have you read this?
https://mysites.guru/blog/joomla-compat-plugin-is-a-crutch/
So in advance of the upcoming Joomla 6.2 upgrade, I saw this:
*The sneaky part: because the compat plugin rewrites class references on the fly, there’s no log entry or warning that an extension is using deprecated code. Everything passes the Joomla pre-update check. Everything looks ready for the next version. Then you upgrade and find out it wasn’t.
- Since I'm already on J6, should I really need this plugin?
Your comment on the error.php is very short.. and not answering my question.
JanK