Care to explain? Seems like she wins the zoning war and shuts down his air mobility. Cheetah's pounce game doesn't seem to get started either and pushblocking hurts her a lot.
I'm just going to repost what I posted months ago.
Blue Beetle's ground zoning out damages hers, meaning most damage trades are in his favor. MB blast is extremely useful in this match up as well as it knocks her down and even if you happen to do trait, you have to hold the blast and get punished. Once you eat your 10-11% off that, we regain zoning advantage again. We also have a unique ability to get around her beams that many other characters do not possess at all and can force zoning hesitation. She has options to deal with flight, but you still force her to have to make a lot of additional reads to snipe you and he can bait her with empty jumps, flight cancelled into fall down etc.
Then there's the up close game. Her post blocked shield bash game isn't good at all. Forward 2 and standing 3, her two fast advancing buttons lose to down 1 shield bash or alternatively if he decides to launch for a full combo he can if you attempt those. She can just walk away and the down 1 whiffs, but then there's no challenge involved.
Her air dash is meh too and Beetle's projectile recovery is so fast that it can be very hard for her to navigate in on his zoning without simply walking in on a life lead.
Up close he does fine against her since he can chip her safely and he is very good at armor breaking her MB back 3/forward 3 and her hitbox is weird so sometimes he passes right through her making them both whiff so there's no risk in that exchange since she is in recovery frames too, he can recover to be safe.
There's no real reason for her to win. Having some options to counter his options just means it's not a body, not that she wins. There is no shut down of flight, he just has to space and think while using flight. He also doesn't have to be constantly flying to deal with her and in fact, I think mostly ground game with flight intermixed from time to time is the key.
As for Cheetah, I feel like this is another case of a linear view of the character. She has entirely too many ways to make you guess on her jump ins. She has pounce cancels, close pounce, far pounce, different jump normals that require different timings to blow up, she can use your anti-air attempts to simply walk you down and when people say her neutral is bad or she has bad footsies, they're not comprehending that this character has a full screen leap that is plus on block and leads to 400ish damage for a bar, more with trait. Her footsies are certainly not non-existent. Her lacking range on her ground normals is completely offset by her insane mobility and reward for catching you slipping with leap into damage.
Now I will say that Starfire has way better options than a lot of other zoners and Cheetah has to play more in depth footsies, but that's why it's even and not in her favor like how she beats Ivy and Fate.
Then there's some other problems Starfire runs into: Cheetah can low profile her MB back 3 and of course since her forward/back 3's are a notable part of her offsetting her highs and so-so mids, it allows Cheetah to get more opportunities to abuse armored forward 3 to crush her armor. Cheetah can also go under strings canceled into up close starburst while taking no damage. She can have a hard time waking up versus Cheetah as well. This seems more like your traditional rushdown/zoner fight.
You can't operate under the assumption that you have some options that check them so now they're shut down. Beetle and Cheetah players that are playing a complete version of them aren't shut down. The good players are going to frustrate you and mix it up.