Alexander, the muscles of most people are not symmetrical. Also, as you have already written, one arm (most often the one that is leading) is stronger - this is normal.
If you see a clear asymmetry of the muscle frame in the mirror, then you need to concentrate on the lagging muscle. For example, if you take all the same hands, then the one that is smaller, you need to put more emphasis: i.e. more reps, more weight, more tiring by lifting dumbbells.
It's the same with all other muscle groups. The main thing is not to overdo it!
It is quite normal that one side of a muscle group, especially a person's arm, is stronger. We need to continue to work with the same weights as before