20 years old Lefty need help with mechanics

Can you check how my mechanics are?
This video was from my bullpen session

What do you think?

your arm is lagging behind your trunk which can give you elbow problems and your trunk is also vertical at release instent of being bent forward which will help with velocity.

Saying the same thing, you are all rotational once your front foot plants and you start to throw the ball. Allow your chest and head to continue towards home plate more, your back will bend, and you will have forward downward momentum with the rotational and should see an increase in velocity and more action/spin on your pitches. Throw over your front knee more, not rotating solely around the front leg.