Previous message reappears in reply box when using Cmd+Enter in Chrome

I am finding that whenever I use Cmd+Enter to submit a message in a reply box, the next time I go to enter a message, it reappears there again.

This is only happening in Chrome (normal version and canary) and doesn’t occur whenever I click the “comment” button instead.

I am running Mac OS X 10.14.6 (18G4032), Chrome Version 81.0.4044.138 (Official Build) (64-bit) and GitLab CI version 12.9.3

Started happening about a month ago. I believe my sysadmin has updated the GitLab version since then.

Screenshot of repro below: