I think there's some sort of limits on how many times per year you can authorize/deauthorize computers. Have you possibly done a lot of either of those actions in the last few months?

Sorry can't be more helpful - but if it is the case that you've authorized or deauthorized a large-ish (as defined by Apple...) number of devices, and you aren't get any better answers here, maybe ask the Google or do an online support chat with Apple.

I'd be talking to Apple, if I need to open a PC to fix my iPhone then they tend to be very helpful, I hate iTunes... 🙄

Have managed to do it on the actual device .

You don't need to remove them any longer. What are you trying to do?

Can you check and see if it's still registered on iCloud.

Mrs Zip has a new phone and I was up to 10 devices so had to remove one.