Hi @auto-phenol and Welcome to the Manjaro community.
The Plymouth package often causes what you describe.
Completely removing Plymouth might solve your issue; it’s generally considered to be unwelcome bloat and many people (myself included) tend to remove it whether (or not) it’s causing any issues; because, sooner or later, it will.
Plymouth isn’t a typical package to uninstall. Because it’s closely tied in with boot processes, there is a special procedure to follow to remove it completely, and safely:
See the Plymouth page in the Manjaro Wiki for the correct instructions to uninstall it; under the heading of REMOVAL.
I hope this helps. Cheers.