Yes, I have ESET Endpoint installed. I had also had it installed previously for Catalina and did not see this issue. I have only had 6.10.460.1 installed with Big Sur for a few days. During that time I have had the git checkout issue around 5 times. I was tipped off that ESET might be the problem by other forums where users set that other security products caused the same issue. It seems like the error may be related to the number of files that are changed when using git checkout. I don't have any actual data to support this, but I say that based on observation. It happens pretty reliably for a branch that has many changes. I now just turn off Real-time File System Protection before doing the operation and have not ever had it happen with that disabled. Hope that helps.
Next year? or did you mean next month?