This is not a Manjaro problem but a user problem.
Decide for one and remove the other.
There has been a couple of topics discussing why it is a bad idea to mix Gnome and Plasma.
Please see Search results for 'install gnome and plasma on same system' - Manjaro Linux Forum
Some even claim it has never been proved it is a bad idea.
Your topic is a fine example of why you shouldn’t mix Gnome and Plasma.
I renamed your topic to reflect the real issue