Whoever needs to hear this: If you too have issues with flickering 5G connection on your Motorola moto g84 5G, it may be a solution to simply use the second available SIM slot.
I blamed my service provider for sluggish 5G performance first. My phone dropped mobile connection frequently. Sometimes just for a second. No solution online. Only posts of other users with the same issue. It seems to be a common problem.
For unknown reasons, switching the SIM slot solves this.