Do not use this tag. It was intended for issues common to Raspberry Pi OS, but Raspberry Pi OS - Bullseye is significantly different to its predecessor. Use the version specific tags raspberry-pi-os-buster or raspberry-pi-os-bullseye.

From May 2020 Raspbian was renamed Raspberry Pi OS (32-bit)

Raspberry Pi OS was a name change to discriminate between Raspbian (the independent open source project) and the 32-bit images that Raspberry Pi builds on top of it.

In Nov 2021 a new version Raspberry Pi OS - Bullseye was released.

There is a 64 bit version in beta release.