No Status or Details by Completing previous backup

It’s still unfamiliar, but I don’t use Docker. I’d note you’re on LinuxServer image.
Are one or both of the joined grey boxes trying to be a bar graph or something?
If you can interpret that image, is it saying that it’s steady at 100% of one core?

You can read about new query in the linked thread here, fresh from developer:

We can hope it’s fast, but we don’t know until some speed testing gets done.

has discussion. Given that it’s still open, I guess it’s not soundly rejected yet.
Recent changes to SQLite and its use have also added significant speedups:

Blog post: Unleashing the power of SQLite to C#

One could see the improvement in Canary releases. I think it’s in Stable now,
but it’s always possible to write SQL in a way that runs badly. See discussion.