There is a potential, for the "folder-move-method" (which is
what I use), to be more version intolerant, than the Export-Import
method.
When you move the folder, the destination version of THunderbird
should be equal or greater. You could move from say TBird 2.0.0.23
to a fresh install of TBird 91.0.
Whereas with Export-Import, maybe you could go from 91.0 to 2.0.0.23.
Normally, the design intent of Export, is portability.
The message format(s) and box declarations probably haven't changed,
but the password and master password concepts have changed with time.
That's when "going forward" on version is going to work better.
I don't know what components are handled in Export-Import as I
don't recollect using it.
Paul