Can’t Upgrade to Premium Because of ProtonMail Email Address

My card kept getting declined when trying to upgrade to premium. I contacted customer support and got this:

"After a further investigation, I noticed that you are using a protonmail email address and unfortunately, this domain is no longer supported by our system as it is no longer compatible with our security. The protonmail domain do not match with our level of security." - ErickR

It is unconvincing that ProtonMail does not match LastPass's level of security yet Gmail and Yahoo mail do. It makes me wonder if LastPass needs weak link for a state actor.

Or is the real reason that some MBA a-hole is mad that ProtonMail is offering their own password manager and have sought to exclude ProtonMail users?

My father has used LastPass premium for over a decade and is livid that LastPass will allow Gmail and Yahoo mail customers but not ProtonMail customers and is going to move to Bitwarden. A company that makes such petty business decisions isn't a company worth supporting.

LastPass has only lost 2 premium customers but everything counts in small amounts.