As I wrote in OP, I used to have this theme/component earlier, but no longer.
So I can’t trace it in either theme or components.
@merefield the topic mentioned by you was closed after the OP found that updating the site solved the issue. But in my case updating the site thru one-click and thru rebuilding, didn’t help.
One thing that has just come to my mind, after @Heliosurge 's post, is that I should re-install the same component afresh, and then check. May be it’d go away.
Will report.
Re installing it and then deleting might get rid of the issue. Maybe something got left behind and is triggering it.
Something to check @merefield would have a better idea. But if your using a full theme that added that component it might be triggered by that even though you removed it. As many full themes package other components in the install.
This link leads me to my themes page, whereas I can’t find any such theme or component installed on my website.
So I thought may be it was the (deprecated) plugin of similar name (my bad that in my prev post above, I wrote ‘theme thru yml file’, whereas I meant ‘Plugin thru Yml file’)
It seems that theme component is removed if it fallback to /admin/customize/themes. I am not sure if you reinstall it will help because the id won’t be the same. Maybe something stuck here and show this update available.
However, if it’s stuck than maybe it indicates the update for wrong theme component too. I saw on your video the Last Seen theme component needs an update and it’s not indicated on your dashboard. It worth a try to update that component maybe it will fix it.
Can you check /logs and browser console too? Maybe there are some relevant warning or error.
And before going. Discourse itself is so deep and wonderful product. How it creates/created the small ‘refresh’ icon to show that updates for this component are available!! Amazing!