unpredictable and random taptic engine thumping

iphone 8 with a home button that failed a couple of years ago. replaced with with a 3rd party JCID brand home button which worked great. within the last 6 months, the assistive touch on-screen home button would popup randomly, but eventually i learned to program the home button triple-tap to turn the on-screen button on and off, so it was a workable workaround. it still manages to appear at the most inopportune time, like when i'm playing a game and appears right where an game action is so when i am trying to attack, i go back to the phone's home screen. more annoying but not a "time to get rid of the phone" level event.

recently though, how the taptic engine will just start tapping away for a while (between 0.5 and 1.0 second intervals) but eventually stop. durations can last a few seconds to over 2 minutes (infrequent). but what also happens during that time, screen responsiveness goes to crap, a lot of times again while i'm trying to play a game.

around the same time this started, the home button has become less responsive, especially when i try to engage double and triple taps. could be related to the taptic or maybe not.

this is definitely weird behavior. i can definitely try a new home button. not sure if the taptic engine would warrant replacing. not sure if there's enough circuitry in it that could go rogue or if the signal to tap comes from the mainboard and the engine is just the mechanical thumper.

any thoughts on how to troubleshoot or what parts may likely need replacing?