how to properly render sequences

hello everybody,
I am rendering videos with the sequencer. All light functions, animated materials and videos look very good in the viewport/preview, but flicker around wildly when the sequence is rendered. The sequencer also seems to randomly change its frame rate. I’m already using the Frame Delay, otherwise the volumetric fog will look totally smeared. What do I have to set so that the sequencer runs at a constant frame rate and, above all, the animations are synchronized with it? If there isn’t, I wonder what the part is for. I have already seen that I cannot record the many animations that are controlled by blueprints. What is this software used for if you can only record a dead world with it? Maybe I’m on the wrong track.