recently I noticed a problem with a git bash just right after I had upgraded git-scm from version 188.8.131.52 to 2.31.1.
Message from the log is: "ERROR [2021-05-17 15:20:54,842]  [SourceTree.Repo.RepoHandlerGitOld] [Log] - UNable to bash start process for 'F:\engine'"
I use system git. With embedded git terminal works fine.
"Use Git Bash as default terminal" in "Tools->Options->Git" is enabled.