The same issue appears on vyos-1.4-rolling-202110180513, ISO downloaded from official site.
Can’t download an older 1.3 ISO than monthly-202011 to find the regression point; the bug is present there (Build commit ID b35660db9bd641)
Edit to add:
Compiled current state of 1.2 crux (Build commit ID 402d80498683f2) and the bug is NOT present. If there’s some place that has an archive of all the monthlies for 1.3 (instead of just the last 12) I don’t mind searching for the monthly where the bug was introduced. Looks like 2020-11 is the earliest monthly.
Edit to remove mentions to a possibly unrelated commit. AFAICT, this could be an issue with the build scripts, even.