Apparently the VAR is allowed to look at the 1m issue for the wall and it has happened before in a Europa League qualifier or some similar match, this is just the first time in the premier league. Its just that commonly the VAR chooses to ignore it in the same way they ignore encroachment for a penalty unless the encroaching player ends up impacting the play by scoring a rebound etc. In this case I guess the VAR decided that what Guehi did was so impactful to the wall that it was worth them enforcing the rule and in previous instances it was not material to the outcome of the play. Personally I don't think it is that consistent because I don't think he has impacted the wall itself, and I do think the referees will be discussing this in their internal meetings as I doubt they will all agree with the consistency of the call themselves, but by the rules I don't think they have done anything wrong.
England
