I think it would be complicated rather than impossible. Worst case, Threads could force accounts to "migrate"; some follows would be lost but following wouldn't be so much affected. This way, you cannot tell what is going on at all, the threads.net handles do not appear to be advertised and the […]

That is not true at all! Moving domains is quite possible, especially when you control both.

Ugh, really? That's the issue I am sure

Something buggy going on. I found the profile on Mastodon Social somehow (a general search?) I could not find it by entering the handle or the Threads URL. I will see if it happens with other profiles.