I'm trying to create a 'spiderwebbing' / 'swirl' effect caused by microscratches around highlights, but for some reason get triangular rays instead of a round halo. I've tried loads of scratch textures and they all have the same problem, even with different sizes/strengths.
The only solution I've found is to use a normal map instead of bump, which isn't ideal as I would need UVs for 100+ objects (or find a way for triplanar normal maps). I've seen other people create this effect with just a bump map, in cycles as well as some other render engines. One solution I've seen for 3dsMax/Vray was to change the "bitmap filtering to Pyramidal or Summed area", but changing Blender's texture filtering doesn't do much (it fixes for eevee, but not cycles).
(The screenshot is slightly exaggerated, but the rays appear with any bump value or texture size. From 2.92 cycles viewport)
EDIT: New images to show difference between normal and bump map. Both use the same texture and mapping setup:
Thanks for any help or tips you can offer