How do you know the address you’re emailing belongs to a business? The head of A&A ISP in the UK used to regularly win ~£100 judgements in small claims from spammers because his personal email was leased for a nominal fee from aa.net.uk, the same domain as his business.

OP had checked that they would like to receive the "Proton for Business newsletter", and on that basis was deemed a "business".

If your email is used as a contact on Business subscription it is safe to assume that it is used for business purposes.

I mean that's cute and all, but it's a party trick, and very unlikely it caused any actual behaviour to change.