I don't think it's anything to do with the Windows version. The number of Defender updates varies quite a lot from day to day.

You have version 21H2 build 19044.1348. That is the current non-insider version so no need to worry.

Probably because they are concentrating on W11.

That's correct, you have to sign up to be an insider.

Not for me. It's still there.

351162

Third PC updated at second attempt. It's ages since I had an update problem.

Lol, yes they are.:-) It's going to be even slower as it failed the first try. Ho hum.:(

Third one failed with missing components, retrying.

Second one updated. Third will take some time as it's old and slow, just like me.:(

Doesn't look like it.

First one done.