For some Brother printer’s using the equivalent open driver (Foomatic) or installing using a PPD file may give limited functionality - depending on how you intend to use the printer.
I agree with @damianatorrpm, either Brother (and other vendor’s) change their installer’s or we have to do stuff like extract the files and scripts from the RPM and install manually. This sometimes works, but is clumsy, not guaranteed and hard is to maintain/update. To make things more confusing some Brother supplied RPMs (I suspect newer models) do install OK using rpm-ostree.
I had a go at extracting an RPM (with mixed success) to address a similar issue involving an Epson scanner (Diagnosing hardware driver installation issues in Silverblue)
For me, I stopped using Silverblue and went back to regular workstation a few months back mostly because of hardware install related issues.