I can confirm such a situation:
In my case I have kept GOS out-of-the-box keyboard, but see a specific app to do the word mesh nonsense, in this case: Track&Graph ( https://github.com/SamAmco/track-and-graph ).
I don't know if that is because of some buggy 3rd-party library, some app-internal keyboard-feature that overwrites the (otherwise flawless) default keyboard functionality, or whatever reason.
Apparently, the bug does not show as a GOS- or even Android-global phenomenon but still is somehow shared across multiple apps. If someone can pinpoint the rootcause, I'd be interested to learn more.