It's worth noting that you technically can't compare these numbers across seasons. These are offensive efficiency ratings relative to the average team that season. In general I think it's still a good comparison and I've compared them across seasons, because the baseline average team can be assumed to be roughly the same.
It's interesting to see where this jump occurs and seems to align with the emergence of the transfer portal. It raises the flag in my mind to ask are offenses getting better or is the average team just getting worse with the talent being accumulated at P5 schools?