doubled/missed characters using Firefox on Android

I have a current Android device running a current Firefox, and I'm having two input problems that feel like a related focus-swapping issue. I don't remember if I've used StackEdit on this phone before, so I don't know whether this is a new issue or not.

I do most of my text entry either with "swipe typing," which uses some amount of cleverness to insert spaces between words, or with voice dictation.

• with dictation: I can go about a sentence before the dictation stops. The first letter of the final word is doubled, e.g. "This sentence will be cut off before I am qquite"
• with swipe typing: about every ten or twenty words, the space-insertion logic fails, and two words run together, "as demonstrated inthis quotatation."