What BIMI is
BIMI (Brand Indicators for Message Identification) is a way to publish a brand logo for e-mail. The domain publishes a TXT record at default._bimi.<domain>, such as v=BIMI1; l=https://example.com/logo.svg; a=https://example.com/vmc.pem. The l tag is the logo, an SVG in the restricted "SVG Tiny PS" profile, and the optional a tag points to a mark certificate (VMC or CMC) that ties the logo to the organization.
A mailbox provider only considers the record for mail that passes DMARC, from a domain whose DMARC policy is enforced: p=quarantine or p=reject, applied to all mail. A domain with p=none does not qualify, whatever its BIMI record says.