Been using this email account for decades. So I still do have multiple nested folders. Yet it seems that further nesting of folders is simply not available.

Nested folders was the whole reason for imap accounts.

Without the nesting there is no reason for imap. Pop accounts would do, and exactly why most want imap accounts.

Please REENABLE nesting of folders as soon as possible. I simply have too many emails in many of my current nested folders.