Ah, this is actually true, just tested now. Scirra still uses the old cordova plugin, which still uses 20.6.
Personally I do not use the Scirra plugin.
For the ones of you who build yourselves you can just bumb the version manually in AS.
DiegoM, many of us switched to community-admob-plus instead of admob-plus-cordova (the community one is a fork from Ratsons, only to bumb the google Admob library version). Otherwise I would actually suggest to re-write it to Ratsons new Typescript one, even though he calls it "alpha" still