Bolares
Legend
I don't get why using the encumberance rules (or my understanding of the rules) make the flier more effective (wich I don't find to be a problem btw).You're the DM. You get to decide this. If you decide it in a way that makes fliers more effective, you can't complain that fliers are now too effective.
Maybe RAW is not clear (I think it is), but Crawford has said that emcumberance applies both to walking and flying speeds didn't he?