Having the same issue with 4.26.1, hoping to get some fix for this soon.
I’ve noticed another issue with Clearcoat shaders since moving to 4.26 - changing the spotlight radius to anything other than the default 0 seems to completely mess the specular on the object with clearcoat shader applied, creating some really weird artifacts.
did a bit more digging into this - problem seems to be coming from the Source Angle parameter of the Directional Light. Keeping it at 0 eliminates the weird shadow patches, but of course that means we can’t get nice soft shadows…
Likewise, the bug I mentioned before related to the Spotlight and changing its radius seems to be connected to the Directional Light issue - I am by no means an expert on how graphics work, but so far it looks like the Specular seems to glitch out completely on Clearcoat shaders when using lights with custom Radius/Source Angle values.