I have Deleted and Downloaded again the podcasts
Now THIS is odd:
some podcasts are tagged in the form of YYYY/MM/DD
others are tagged as DD/MM/YYYY
for no apparent reason.
This happens even for podcasts of the same subscription, some tagged one way, others the other way.
Now I am confused.
EDIT
Changing the short date in Windows 10 totally messed up MusicBee podcasts dates: now it's impossible to sort them by title and some episodes have impossible dates like 2020-12-03 (and we are now in july)
Looks like a bug, don't know if in Windows or MusicBee, but this doesn't work fine for sure.