Sorry for bad english I am not a native english speaker.

I searched on net and I couldn't find anything related to it. I am left-handed which means my left hand used to be stronger. For about 1 month now I have been making some amazing strength gains on bench while bulking,but my left hand is getting significantly weaker than my right hand. I push the 1rm weight easily and fast with my right hand while my left hand gets later on top,shaking on the whole range of motion and sometimes I am not even able to get it on top without help from my spotter. It DOES NOT hurt. I warm up really well always. What could the problem be?

edit: I do Push day right after Pull day (where I do Pull-Overs)