After adding support for verified brand logos in 2021, Gmail is now going further by adding a blue checkmark to emails. The existing system is based on the Brand Indicators for Message Identification (BIMI) standard, where brand logos appear in the “avatar slot” next to the sender’s name and address. For example, instead of a generic “B” against a plain background, Bank of America can show its official flag logo.
https://9to5google.com/2023/05/03/gmail-blue-checkmark/