I'm not 100% sure of exactly all the characters that cause this behavior, but one example is if I long press the d to pick the & symbol, when I try to flow the next word, it seems to ignore where I started and begins resolving to words that are nowhere close to what it's supposed to be, plus as I continue swiping, other unrelated words keep appearing.
If instead of long pressing, I select the symbol from the number keyboard, it behaves normally. But that defeats the convenience of being able to use the long press.
This has been happening as far back as I can remember, on multiple devices (Note 8 & 9). I just finally got irritated enough to post about it. I couldn't find another post on this, but I I didn't spend much time searching.