We have a new set piece coach this season. It's obvious that Pep unlike Arteta is not giving him the time to work on attacking set pieces with the players. Foden just floating the ball in, seems to be our only way , a waste of time , so easy to defend. Arsenal look dangerous from every one.We've scored the same amount of goals as Arsenal.
The flip side to your argument is Arsenal are far too reliant on set piece goals and not scoring much from open play like us.
Sure, adding threats of goals from corners etc would be nice, but we're not doing too badly scoring.
I'd say a bigger problem is we're completely reliant on Haaland.