Every so often the Shimano 105 7020 hydraulic disc brakes on my road bike start to make a metallic grinding noise and I can feel additional resistance when riding. The culprit has always been misaligned brake calipers on both my front and rear wheels. The fix is simple: throw the bike on the stand, loosen the caliper bolts, spin the wheel, hit the brakes, and tighten the bolts.
I'm wondering why the calipers fall out of alignment in the first place? When using the brakes while riding you're forcing them into the correct, centred position - basically the technique I described above to fix them.
I can also imagine that the calipers might move around due to other forces (bumps, etc) and hitting the brakes doesn't apply enough force to centre them. In that case it probably bends the rotor a bit. The solution in this case is to tighten the caliper bolts more but I already use full force with a screwdriver and don't want to risk doing any damage to the fork posts with a wrench.