It’s happening on a self-hosted instance I administer (2026.6.0-latest), but not on Meta.
In the message field, whenever I type ', it is auto-translated to › or ‹, making it very difficult to write anything. Just like in this topic from 2019.
Default Locale is French.
This was fixed in the past few days. It should work on your forum similar to on Meta after you performed an update.
I have updated to https://github.com/discourse/discourse/commits/122c1444db222f83631849e8b18aa9390e32d371 and the bug remains.
The version you linked is two weeks old. I don’t expect that to include a fix added this week