Hello LionelDenny
i just checked again:
when Bitdefender 2021 (Version 25.0.3.24) with all latest updates installed is active, then i get the dreaded 'insert disc' message when i want to start MSFS2020.
So i can not confirm this has been fixed from Bitdefenders side.
Hopefully they will fix it asap.
update:
i just even tried to add a rule manually to Bitdefenders Firewall
it was not possible, since BD would not let me add a rule to the flightsimulator.exe which has 0 bytes