OK had more time to think and having read some more post match reports, and I think we're doing Arteta a bit of a disservice in that I now think there IS a pattern/intent to the play, and it basically looks to replicate the pre-COVID pattern seen down the left in the final 3rd.
Pre-COVID our open play was described as a 235 / 325 depending on opposition & player availability. Initially we saw Xhaka dropping into the backline, whereas in other games we saw Sokratis start as RB and then play CBR in a back3 in open play. I think this was more to do with Sokratis' ability as CB rather than as replacement for AMN as RFB/WB.
We know this pattern was used to enable Saka to play as winger outside PEA in the final 3rd.
Prior to the resumption of play there was an article I saw that described Saka's new role as #8 as being a copy of the tactic seen at MC with KDB and B Silva both overlapping outside the WFs to attack the by-line and cross the ball into the area, with the WFs making runs into the channels to the near and far posts.
Against Brighton we saw Saka do this repeatedly in what replicated the same pattern seen pre-COVID. The risk in this is if he doesn't look to overlap with the intent to get to the by-line and cross the ball, and if we're playing with a back3 with the LFB staying deep it leaves a hole on that side just behind the attack.
On the other side we saw a difference in that Pepe stayed wide to isolate his FB, whilst Ceballos looked to play in the half space.