And…
There could be something in that 
If you can, record an effort with Kinetic-»TR & 4iiii-»Garmin, then compare the numbers across intervals. Through-axle bike on a trainer designed for QR has been discussed here, & it looks rather troublesome. Also consider temporarily installing the 4iiii meter on the bike that you were using on the trainer.
When you were doored (sorry to hear that, but good to know you’re back on the bike! 
) did your bike fall on the side with the power meter? It’s possible that could’ve upset its sensitivity too, not just the offset.
If you haven’t already, I would strongly urge you to determine the cause of the blackout, before trying an FTP test on a moving bike. Falling off rollers & crashing in a loungeroom seems more favorable than blacking out onroad & getting rashed up by skidding to a halt, or worse, run over by traffic.