Hi, I use SwiftKey for several years. Long it's been a superb keyboard. However, I wanted to share an observation I have had in last months. I have noticed that accuracy of flow writing got significantly worse, at least for Slovak language. What I mean is that I use flow writing for some word, often being careful to move across the correct letters but the keyboard suggests completely different word than I meant. Hard to say when it started, I would say it's less than half a year. For the English, the experience is still fine.
It's difficult to be very specific about this. It's more about the overall experience that used to be more pleasant in the past rather than specific words.
Also, I have used typing in English and Slovak simultaneously and the keyboard used to recognize which language I want to type in, missing my intention very rarely. Now I have more mixed results. It happens more often that I want to type in Slovak but the keyboard suggests words in English. It sometimes suggests English words even when I turn off the English in settings. Now I usually have turned on only the language I want to type in.
I am not sure whether this observation can be very helpful but maybe if you have done some changes in inner workings of the app lately then this could show it had unwanted results.