Operating system: Win 10 18363.535
Graphics card: RTX 2080 Ti
v 2.81a (tested in new alpha and beta releases also)
Short description of error
termintor problem (pixelated pattern showing up when using bump map) showing up in cycles when using a bump map. this error has been reported in the past and stated to fixed in new versions, but upon testing these new versions. it looks like it is still present.
The issue tracker page linked does suggest that they've mitigated the problems in newer releases but the same thing occurs even in the 2.82 beta and 2.83 alpha so unfortunately, updating doesn't help.
Exact steps for others to reproduce the error
attached is the blender file - the error can be seen in the shirt. upon further testing, it can also be seen in the skirt when a bump map is applied to that also. so it doesn't seem to be the model or bump map.
here's an image of effect: