You are mistaken - Manjaro is not holding updates back - the goal is to keep stable branch as stable as possible. AUR is targeted Arch packagelevel - this cannot be guaranteed on stable branch.
Third party repositories is equal to custom packages and custom packages is officially unsupported
- if you get issues you are on your own
- no matter the name
- no matter the build
- no matter what you read
Please educate yourself reading the following articles
If you request help with your Manjaro system - in order to do so - any forum member may require you to revert your system to a pristine Manjaro environment.
Only then can your issue be identified correctly and the appropriate solution applied.