I made some changes recently to our backup schedule and I was reviewing the history when I noticed this oddity:

Two templates took almost the same amount of time to complete as the synthetic fulls. Looking at either of them shows just a few minutes to actually complete.

This was a little baffling, but not really a problem - just a minor error in timing on successful backups, no biggie. Today I was able to capture a job creating a synthetic full in action (normally it runs at 2am and I wasn't that curious). You can see that on the left, the VM was successfully backed up, but on the right, it shows as still processing and the time is increasing. There are other templates in the job and they all show similar behavior.

On days where these jobs do not create synthetic fulls, there are no timing issues with the template VMs, and non-template VMs never have the issue.
I am running Veeam B&R 9.5.0.1536, which I believe is the latest. Is this a known issue? And yes, I know that I should probably open a case but due to $reasons I cannot open it from the web and I don't have time to call it in right now, so I figured I could ask here at least.