Both Samsung and Apple USB C to 3.5 mm adapter work fine.

Have no issue since June update, may be issue with particular batch?

Google has stopped support for Indic keyboard in Android 12, nothing to do with Samsung. Do a search in Pixel forums, you can see for yourself. Also try to be a better person and less of an uncultured punk on the internet.

Use Gboard from Google. They have stopped Indic Keyboard and integrated that into Gboard app.

Not me, no issue here.