When I swipe “don’t” in Gboard, at least 30% of the time it decides I mean “didn’t”. I just tested it, and the accuracy was shockingly bad. I’d understand if the strokes were very similar, but “didn’t” has a whole extra stroke in it compared to “don’t”. WTF, Google?
For it to do that, “Auto-Correct” in the Gboard settings has to be on. You can also kind of accidentally kill a feature like this by having a single lowercase i added to the dictionary. If you have, just remove it like someone showed above. Note: there is no list of words in the options anywhere where you can see the list, you can do it while typing anywhere though. Just type a single I, press space, then backspace, then drag the single “i” entry from the suggestions to the trash that appears when you hold the i.
side note: I have typed this comment using Gboard glide, and I had to correct a total of 2 words. Everything else was recognized as intended.