I don’t know if this addresses the problem of the OP but here’s my experience since the new 17.4 update…
My Siri remote lost volume control of my AV receiver after working fine for over a year (ATV4k latest gen). When I pushed a volume or mute button, I got the circle with line through it on the screen with ATV as the source. (As if that function was not available.)
Called apple support and went thru the reset, delete remote, reinstall and learn the remote “dance” with no change. Escalated to the next level…
While working with the escalation engineer, I stumbled on what seems to be a workaround….
I did the “learn remote” cycle again but this time I used the AV receiver’s IR remote to program the vol-up/vol-down/mute buttons. VOILA! All of a sudden, the Siri Remote volume & mute buttons worked. I renamed that new remote “AV System”, selected it as the device to use and went back to normal use. I did this while the escalation engineer was puzzled. We decided I created a workaround to this new problem that may be associated with the 17.4 update.
Conclusion-It seems the update erased, eliminated or otherwise deleted any IR references to the ATV Remote volume settings. Using the original remote, I reprogrammed a point of reference for the ATV remote to duplicate (clone?)
I’d imagine Apple will incorporate a fix in future updates. If it goes crazy again, I know where to look.