I think you’ve already diagnosed your own problem here, but to be clear for readers: In this screenshot, the orange line is not the for_testers branch! In Git, branches are pointers to particular commits, and both master and for_testers point to the same commit.
The orange commits appear to be abandoned commits to which no branch is currently pointing. (In vanilla git, those commits just disappear when you switch the branch to point somewhere else; in Anvil we deliberately keep them around so you can use them later if you want to.)