Currently Proton is displaying a black lock icon when the email is "stored with zero-access encryption", which is the worst case when using Proton Mail, since all emails are stored this way on Proton.

The icon becomes blue when the email is sent or received securely with the recipients/sender (green when PGP).

It'd be less misleading to have no icon at all in the case of the standard case (stored with zero-access encryption), and keep the blue (or green for PGP) icons in the other case.

It'd also makes Proton Mail more accessible to people having difficulties to distinguish the two close clolors (black and blue).