Anyway the vast majority of games on OGS are without handicap, so I don’t think handicap games creates a lot of drift, if any. Many other factors may influence the rating system, like
Entry rank chosen by new players
Sandbagging and other forms of cheating.
The rating system of OGS was designed to be intermediate between EGF and AGA. A survey was made last February
unfortunately it didn’t receive many answers but it showed no evidence that the ranking system had become harsher.