Testing version: Version 2.0.14 on macOS, in both Ventura and Sonoma.
What were you doing: Using the app normally
What feature did you use: Using the app normally.
What happened: The built-in background grayscale image of the astronaut Bear floating in space is showing through the scrollbar attached to the Notes list.
What did you expect to happen: For the scrollbar to not show the scene of an astronaut Bear floating in space. 
I noticed an irregular splash of gray in the Notes list scrollbar a few weeks ago while using the app on Ventura — it was a similar enough shade to the scrollbar widget itself, that I took it at first to be an artifact of that. However, it persisted through moving the widget over the space, between the three Show views (Editor, Notes, Tags, and all combos), and between restarts.
It was only today that I realized what was going on when I resized the Notes lists by dragging its right edge back and forth — the bottom gray smudge slid away, but another smaller one appeared above. Turns out they were stars in that astronaut Bear floating in space.
None of the system settings regarding scrollbars nor the accessibility display settings like “Reduce Transparency” made any difference either. And changing Bear Themes did not help.
