Music stops playing on Apple Watch every month

Apple Watch SE 1st generation, iPhone SE 2nd generation.

Every month since about 4 months the watch stops playing music. Trying to play it seems to want to start but then stops.

What I then have to do is to unpair the watch from the phone, pair it again by setting it up as existing device from backup. This takes many hours but then the watch plays music again.

Until next month. Then the same again.

I want to avoid having to spend all that time every month.

Why is that happening?

My suspicion is that it started happen around the time the SE 1st generation disappeared from the Apple website - meaning it is no longer officially supported, and it gets no updates. The problem seems to come every month around the time when the iPhone updates itself.

So is the reason that my watch is simply no longer supported? I hope this is not an intentional step from Apple to get me to buy a new watch ...

Does anyone else have this problem? Any solutions, apart from the time-consuming unpairing / pairing activity?

[Re-Titled by Moderator]