Vivaldi: On autoupdate the side panel is forcibly re-added and opened

Every once in a while my Vivaldi browser suddenly pops up a completely empty side-panel, showing an entry that wasn't there before. When I hover this button it says "Stylus / about:blank" in a tooltip. I don't need that panel, so I delete it. But once every few weeks it keeps re-appearing again and again. As I later realized, this happens every time Stylus extension gets an update.

For instance, I've just got another such jump with a new panel, checked Stylus subdirectory in the browser profile extensions subdir, and sure enough, it's date/time showed that the update happened at this moment.

How can I prevent this panel from being constantly added back?

System Information

• OS: Windows 10 22H2
• Browser: Vivaldi 8.0.4033.54 (Chromium Version 148.0.7778.282)
• Stylus Version: 2.4.9 and earlier

Screenshot