Another user's name is appearing on my lemmy.ml front page

See the images attached to the linked bug report. Where it usually says my username in the top-right, another user's name appeared. This happened twice in the last two days.

I submitted the bug to the lemmy-ui project, but I'm not certain if this is a lemmy-ui problem, or a problem with the specific infrastructure setup of lemmy.ml, or even a backend issue.

Any advice on whether I should post this bug report to somewhere else for greater visibility would be welcome. This could be indicative of a fairly serious security issue (or it could be a completely cosmetic bug).