We seem to have narrowed down what’s causing the issue with Inky pHAT. That is to say we have managed to damage multiple brand-new displays in the same fashion, and they’re progressively getting worse exactly as you’ve reported. To counter this, we’ve also managed to run multiple displays for the same length of time, under the same conditions and have them not display any faults at all.
Sorry this process has taken so long. Our enemy in these tests has been time- we have to balance getting this solved swiftly, with how long it takes for issues to manifest.
Right now we need to explore in some detail why it’s happening and then come up with a fix, report our findings to your good selves and get replacements to those who need them.
I think it goes without saying ( at least I hope it does ) that we’ll do what we can to make this right.