Greetings DeadPixelPro,
It sounds as though you’re having issues with applications not remaining in the folders you’ve created within Launchpad, and Launchpad rearranging your apps. Apple Support Communities is a great place for help, and it sounds as though you’ve walked through the following article to arrange and organize your applications.
Use Launchpad on your Mac
Since you’ve restarted the Mac, and noticed the issue afterwards. Have you verified you’re running the latest macOS? If not, updating macOS is a great step to help work towards a resolution.
Update macOS on Mac
If you’re running the latest macOS version, are you noticing if this issue happens in a guest, admin or standard user account? If this is happening in a guest user account, you will want to see if this happens in a standard or admin user. If you want to create a new user account to test the issue, you can find the steps for doing so in the following article.
Set up users, guests, and groups on Mac
We look forward to your response!