Second, the left chest shows that you are a "right-handed", which is normal, because the right side is more flexible during exercise, which means that the muscles are more coordinated and easier to borrow, so the stress on the chest muscles, the core of training, is not so obvious and the effect is similar;
Third, if the proportion is really uncoordinated, I suggest you use a dumbbell bird with one right arm to adjust it. Be careful not to need heavy weight! Multi-times, multi-groups and larger movements, focusing on the feeling of peak contraction, while maintaining the balance of the left arm with a slightly lighter dumbbell counterweight.
Fourth, strengthen the right chest muscle with Smith frame. Needless to say, right?