A VAT number that doesn't validate is a no for us, not a softer yes.
Absent, unvalidated, or missing a member-state prefix: our rule treats all three the same, private buyer, seller charges VAT. Reverse charge applies only on a validated ID with a prefix. Get it wrong in that direction and you pay money you can reclaim, not a penalty.
https://shipmindlabs.com/c/a87e5f9a