I've been using Garmins since the fenix 2, and I'd always found my FTP changed only occasionally, as I'd expect. However, over the last few months I'm finding I get a new FTP virtually every ride, 4-5 times a week, with it generally fluctuating +/- 10w. Given that FTP should be relatively static, I would expect that once Garmin felt it had calculated it, further activities would just lead to ever-reducing refinement based on long-term trending, but it seems to be re-calculating it every ride with a big bias to the ride I've just done, e.g. recovery rides always lead to a big FTP drop.
I know that I'm given the option to Accept or Decline a new FTP, but that also seems to have been borked for a while too - rejecting it just seems to mess up TrueUp syncing.
Anyone else getting this? I'm on the current beta, but I've been seeing this for months now in public releases too.