Can you please fix the problem. There are different manjaro users with this problem (see issue) and no user of a different distro has posted about this problem.
It looks more like, as it is with most packages, that this package comes directly from Arch (not maintained by Manjaro separately).
And in Arch, it is flagged as out of date since September 15th 2024
Notes-up starts fine here; tested on KDE Plasma (Stable).
Your problem is likely specific to your environment.
To verify this, please create a new User account and test launching the app there. If it launches as expected in the new account, then there is no issue with Notes-up itself.
You might also consider replacing Notes-Up perhaps with Obsidian, for example: