I Phone 13 synch with windows itunes

Today when I synched itunes (windows 11, current itunes) to Iphone 13, most, (98%) of music did not synch and says "this song is not currently available in your country or region". It has been working fine till today

My 2 old ipods synch normally and music comes out the right way and my new and not so new Ipads synch properly that all the music is there-so it must be an iphone 13 problem .

I have rebooted iphone, PC, reinstalled 17.4.1 system, and am running out of ideas, but have not restored the 13 yet. Only thing I "played" with today was "find my" app, with notifications on and off . But that shoudl not change anything.

Any ideas?