Arsenal second goal from the short corner ,lad said possible offside from the actual corner kick, looking at it many times it looks like the linesman more concentrated on the ball
You can't be offside from a corner.
"Some Villa fans questioned a possible offside on the short corner which led to Arsenal's second goal, but you cannot be offside from the first play of a corner routine."
Yep, this one is pretty simple, you can't be offside if you're behind the ball and you're automatically behind the ball when a corner is taken (because despite the option to physically move the ball around in the quadrant it's considered to be on the goalline in the laws).
The 'real' 2nd controversy that everyone has forgotten is that Saka should've been sent off for his challenge on Moreno. Take him out of the game with us leading 2-1 and I think it would've had a massive impacts on the result, especially given how important he was for them in the 15-20 minutes after half time.