Hi, @surfrock66, @ricmarques!
This issue is quite funny.
It looks like some icon is being displayed incorrectly instead of another.
I assumed it contains UN in its name. Quick automatic search through my icon folder has found a perfect candidate: /usr/share/icons/Yaru/scalable/status/un.svg. Note this is the .svg file, so it scales perfectly.
But what icon is the correct one? Another perfect match is /usr/share/icons/hicolor/48x48/apps/un-reboot.png, where UN stands for Update Notifier. So, when you have a pending update, the wrong icon is displayed, it looks for un-reboot.png, but finds un.svg and displays it.
Probably, renaming /usr/share/icons/Yaru/scalable/status/un.svg is enough to fix this.
Hope this helps.