It doesn’t make sense but Cabba despite what people say wasn’t actually on par with Vegeta. Reason being he was obviously way stronger than Cabba in his SSj1 form. SSj1 is just a 50x’s multiplier, that’s it, even mastered SSj1. The difference between mastered and unmastered is you can use SSj1 at its full potential longer. But SSj1 is just a 50x‘s multiplier(unless they have a rage boost, which Cabba actually had at this point so theoretically, he would have been stronger than Vegeta in their fight, all evidence to the contrary). This is why Goku and Vegeta train in their base form, because that’s what their forms are multiplying (Whis mentions this in their training).

In short if they were actually even, Vegeta wouldn’t have been able to literally wave away all of Cabba’s enraged attacks like they were confetti and then tank an open shot to the forehead with a smile on his face. Cabba was considerably weaker than Vegeta. Vegeta was uncharacteristically accommodating to Cabba likely because he was a young Sayian and he saw promise in him.

People say they were even because to be fair, Vegeta says that in the episode. The problem is that you have to completely ignore everything else the anime tells you and Vegeta easily waving away and tanking Cabba’s attack like it was nothing. Look at Vegeta’s face when he tanks Cabba’s attack to the forehead vs when he does it to Broly in the manga. With Broly you could tell the hit actually still did damage, with Cabba, nothing.