Republicans have a pretty heated Senate race going on here. Also, Trump was still getting big turnout in primaries in other states.Big picture yes but in a primary, where the incumbent isn’t even on the ballot and if there were no other races that would push turn out, I do think that needs to be taken into account.
I’m not saying it’s not something to watch but I think saying it indicates Georgia suburbs have gone blue might be an overreach.

As for the Atlanta suburbs, I think all of the major metro counties went blue in 2018. It's middle and south Georgia that you have to worry about.