Apparently "+Google Photos" is just the nickname of the "Google Photos" account on "Google+". The name of the service is "Google Photos", not "+Google Photos".
2018(jan-aug) - ABC Photos
2018 - ABC DOREMI
2019(jan-feb) - ADORE ME Photos
2019 - Adore.me
2021 - Adore.me & Analphebet.photos
edit: To me, the problem is that they're using `Google+` as branding, and `+` as an identifier like `@`.
> Goodbye Twitter@ Photos, Hello @Twitter Photos
Would be equally weird, imo. (Albeit, less weird because we're used to @foo and #foo)