If you are using calyx or graphene, It's the keyboard. Use unexpected, Anysoft, florisboard beta, Gboard, or other modern keyboards. The default, AOSP is too old and not really maintained anymore.
Discussion
nostr:npub1gcxzte5zlkncx26j68ez60fzkvtkm9e0vrwdcvsjakxf9mu9qewqlfnj5z thanks you're right it was the keyboard.. I was using #Openboard and It was crashing.. I have switched and It works fine 🎩
If anyone have encountered suddenly Amethyst's crash when trying to tag a user.. try to switch to an update keyboard like Gboard.. 🎩