Protobuf is being built inadvertently using the local version of Abseil

[Jobanny-Friki]

From version 21.12 onwards, Protobuf includes the ABSL_PROVIDER option, which allows you to choose between the Abseil version from the local Git submodule of the Protobuf package and the system version. So why include Abseil as a dependency if you are using the local version? You are not using -Dprotobuf_ABSL_PROVIDER=‘package’, so you have been using the local version from the outset, whilst including an unnecessary dependency. If this is not the behaviour you want, use the option mentioned above.

[cbix]

protobuf-21 and abseil-cpp were both added to allow building ola, which requires C++11.
It was probably assumed that abseil-cpp is the only abseil provider at build time, so I didn't look into those build flags.
Looking at some GitHub comments on the ola project there's some hope they could get out a release bumping the C++ standard, that would allow us to fully remove the legacy abseil/protobuf packages.

[Jobanny-Friki]

If you are going to stop maintaining the protobuf-21 package in the AUR in future, please find a new maintainer or leave it orphaned; there are other packages, apart from ola, that depend on it.