Or I will try bumping biber package.

Only bumping biber won't help. Because It will be again automatically pushed into a separate update. I do not want rebuilding texlive. I will try unobsolete the updates and waive gating.

This inability to manage updates in Rawhide is really stupid.

Both pushed to stable.

You can manage side tags updates in Rawhide. Just not the non-side-tag ones.

By tagging the builds to f39-updates-candidate, they were treated as non-side-tag builds.

Instead of tagging, once the builds in side tag are done, you create the update in Bodhi web interface -- https://bodhi.fedoraproject.org/updates/new Use Side Tag in top right corner of the Builds section, or via CLI bodhi updates new --from-tag f39-build-side-66666.

What made you think that tagging to f39-updates-candidate is necessary/helpful? Is there some outdated documentation that suggests this?

It's not documentation, it's how I usually manage side-tag builds for EPEL when adding a chain of new packages. There --from-tag is useless because I incrementally add new builds.

Incrementally adding new builds to rawhide update is not generally possible because the update will go stable faster than you will b able to do that. But until i does (e.g. because it it stuck on gating), you can add more builds by building them in the same site tag and than "refreshing" the list of builds (I only know how to do that from web UI).