Hi @Chris Net ,
Indeed, there appears to be a difference in how gMSAs interact with the system when compared to traditional domain accounts, in that they actually are interacting as a service rather than as a batch job. As a result, they actually require the "log on as a service" right rather than "log on as a batch job", even for scenarios where traditional accounts require "log on as a batch job" (such as scheduled tasks or running IIS app pools). I have never seen this officially documented anywhere, but just found it by combining bits and pieces of info I found in various places along with the results of my own testing. I wrote about this in detail in my answer to a similar question here:
Hope this helps!
Best regards.