So apparently some people are thinking Bakugou is genuinely angry/upset that Izuku is complimenting him here?
First off, the speech bubble-biting is meant to be a joke. It’s meant to be funny, like Bakugou’s exaggerated expressions often are.
Secondly, Kacchan vs Deku 2 is fairly recent. Before that, Bakugou assumed Izuku was constantly looking down on him, and took his words and actions are such. Now, that misunderstanding has been cleared up. He’s aware that Izuku’s admiration is genuine. Izuku’s so upfront with his appreciation of Bakugou’s new costume, and Bakugou’s not used to interpreting this positively.
The most likely reason for his behaviour here is… he genuinely doesn’t know how to react. He’s not used to this. He’s been complimented his whole life because of his Quirk, but this is Izuku in particular complimenting him, and he knows Izuku means it. He’s not prepared for that after so long thinking Izuku’s words are mocking, so this is what he defaults to.
Not to mention, post-Kacchan vs Deku 2, Bakugou complimented Izuku himself, although the translations don’t exactly convey this correctly; he was telling Izuku his punches pissed him off because they caught him off guard. It’s a good thing.
Basically, in regards to Bakugou and Izuku’s interactions, given the complexity of their relationship it’s important to look back on recent events to analyse why exactly Bakugou is reacting this way.
(This translation is from Viz, thank you to @catmonsterscupcakes for letting me use it!)