I just built a bike using TRP spyre flat mount brakes and a SRAM 140 to 160 rear adapter and had an issue with the adapter not exactly matching the caliper. The SRAM adapter had a recessed area for the brake to mount on the adapter and the TRP caliper had a sharper radius corner(more square) than the recess, which caused the caliper to hang up and not sit flush with the adapter. It was easily fixed by putting the adapter in the mill and cutting a bit out of the corner, but there are some inconsistencies between brands.