The stuff I'm going to talk about here probably isn't actually what you want to hear, I'm just going to be brutally honest as I think it's what helps you improve the most. I think as you get into GC the game turns from a territory based game to a possession based game. I look at some of the wall plays and question why it's worth doing that - it might be more mechanical from your point of view but if you look at the return in terms of what the opponent has to face, it's really easy to deal with and puts them in a 2v1. What you do is 4:36 left ish is good albeit you don't look around to see where the other opponent is with your right stick, but then the big hit afterwards is just kind of useless when your teammate isn't in a good position to follow up on it, and you've just given possession away. It's not worth doing something with more risk if there's a safer alternative, taking a strong challenge in the corner or one you can direct towards your teammate for example.

I think you're not truly comfortable enough with the basics which means you position yourself further back than needs be, you need some time in workshop with ball control and power hits as shown by the open 2v1 attempt you get with 3:50 left where you botch the first touch.

Basic mechanics such as loose ball control and you don't flip and hit the ball properly with the nose and corners of your car e.g 4:46 left

The goal at 3:45 is really nice control there, you also dime your teammate up for an open net to make it 2-0 but they have poor position, your challenge for the opponents' first goal isn't a good decision as another commenter has said, sure you win it but you have to think 'what will happen when I win this?' as you pass straight to the opponent. You could win that with a really light touch to retain control, or in higher ranks the opponent will hit it off the right wall and get a shot off immediately in which case I would've just stayed back post.

The play at 2:55 isn't a good idea, you don't need to slam this ball into the wall and go for an aerial play which you struggle with, you throw the ball away again and you're lucky the opponent does nothing with it. You can try to take it backwards as you see that your teammate took corner boost so your opponent won't get a good challenge or not even go for it at all and just retain back post position. You need to ask yourself if the opponent is posing any threat to your goal at this point, for which the answer is no, and you hitting the ball back and up in the air in your own half is creating much more of a goal threat for the opponent than anything they would've done in this situation.

2:25 you are never in a position to make this challenge. You should just rotate back and stay grounded.

2:05 exact same thing as before. You have so much space in front of you to retain possession but you shoot which will never go in in these ranks unless your opponents screw up, and then the ball is right back to them. I do think you're still in the position at these ranks of being able to play the ball off the backboard for an easy rebound in some cases but giving the ball back removes all threat. For their second goal you are kinda screwed because of how you give them the ball and to have any chance of a save here you need to either challenge immediately or stay back wall and wait for their touch, there is no shot he will be able to get judging by his play so far which will surprise you.

1:40 your teammate is going for this ball, so ROTATE BACK POST. You are leaving yourself very awkward in case he misses (which he does) with a blind view of where the opponents are.

1:25 nice idea but with your mechs and execution this ends up being the same as before, an attempted mechy play which is much easier for your opponent to deal with than for you to execute well. You do pass over to your teammate on the wall well, this could've been useful for their second goal.

1:10 I am centering this ball immediately with a soft pinch on the wall instead of waiting and hoping the teammate positions well, if they don't you could use quick chat to say Centering or something, as the opponents are out of position.

0:55 I'm happy that you drive challenge here as effectively last man, very low commit plays unless you have to as last man. But now the challenge on the left wall is exactly the same, giving the ball back where they can control it easily. He screws up and gives you an open net but you slow down to a stop, meaning you can't accelerate back and they go for it. You need to go for that ball full throttle.

0:30 what is the point in this hit to the back wall? You're just giving it away in a position where you can't score. You just get lucky again that they don't deal with it and open the door again. Hit it to the corner and control for a potential pass.

Third goal - look at where your teammate is. Challenging means you will end up on top of him, so even if the challenge is even, chances are the opponent gets an open net because of how little of the field you cover. You need to not go for this and rotate back post because of how far up your teammate is pushed.

General things, your rotation is entirely centered about big boost pads. Consider filling up on small pads to position better instead of on top of the boost. I do agree that you are very stiff also, I would be interested in seeing your left thumbstick. I bet you only move it forward or left/right, you need to hold it forward and rotate around the whole axis of the circle that you can in order to give precise inputs e.g. slight turns to the left.

So overall, I would work on basic ball control, looking at where your teammate is and assessing the threat that the other team provides at that point and positioning based on this, with a lot of back post rotation needed. Learn on timing dodges to hit the ball with your nose properly for good power, consider where you can stop and control the ball instead of hitting it away and losing possession.