Immediately logged out of iCloud

Hi,

For the last month or so, whenever I login to iCloud and start browsing emails after a few seconds it kicks me back out and asks me to login again. My email is basically in accessible.

I'm using a PC on Windows 11.

It doesn't matter which browser I use (Chrome, Microsoft Edge)

I've tried clearing all cookies and browsing data

I have nearly 2TB of free storage

I've phoned Apple and reproduced the issue over video call for them and they've said they are noting it down - but I've heard nothing

Has anyone had this issue and more importantly, found a solution!?

Thank you!!