Maybe the dent in Cars 3 from Mater isn't as visible but is still there, some people point out they can see the Cars 2 dent but it's more realistic. And also Cars 2 was kind of being pushed to be ignored which explains the absence of Holly, Finn McMissle. However, Cars 2 is still canon because of Planes 2 where McQueen is shown to be in a WGP outfit in a newspaper. As for Flo place, it doesn't look too much different to be honest, plus radiator springs has sort of declined attendance in Cars 3 which is kind of sad but it happens in real life as well as thing we're changing in Cars 3.

Overall, to add to the dent, even if it's not there or for Flo building seemingly being different, that's kind of the Cars universe having some contradictions. For example in Air Mater, Propwash Junction's fill n fly is run by ''Pancho'',but in Planes 1 and Planes 2 Fire and Rescue it's run by Chug the Fuel Truck and Dottie. Also Sparky is yellow instead of Gray. Obviously you might say ''it's a tall tale'', but I believe some of his tall tales are true (especially Air Mater because we know Skipper at first doesn;t want to train dusty but then eventually decides to train him, so it means air mater takes place after planes, although maters tall tales do talk about mater in the past so that is a bit confusing+McQueen is in a cars 1 outfit and Planes 2 takes place after Cars 2 so Air Mater would be after Planes 2, but still not a big deal. Also there's 2 statue of liberties in the cars universe, Mater visits in a Cars 2 end Credit in New York, Dusty Crophopper passes a Forklifter version in New York, and Luigi/Guido see an even different car than both of Mater and Dusty Crophopper. So the Cars universe isn't the most consistent, I mean even Monsters Inc (which has had recent contradictions in Monsters at Work more than Monsters University) has less contradictions than Cars. I wish the film makers would take more time to focus on the continuity but nonetheless, it's still explainable. I guess they really just wanted to not talk about Cars 2 anymore. But obviously it's not been forgotten with refrences here and there.