The moment Poe cracked a joke at Kylo Ren’s expense in front of the stormtroopers and Kylo not reasserting his authority by gut-punching Poe or something at the very beginning of TFA effectively ruined Kylo Ren as a villain right from the get-go, and Kylo’s lashing out whenever come off like the temper tantrums of a spoilt brat. That’s the biggest problem with Kylo Ren, he doesn’t feel the least bit menacing, and as Snoke says at the start of TLJ, he’s bested by a girl who had never held a lightsaber.
That’s kinda the point, and one of the things that made Kylo Ren such an interesting Star Wars villain. Unlike Darth Vader or the Emperor (or even the prequel villains), Kylo is a total wannabe poser. He projects this fearsome persona that evokes his grandfather while in reality he’s a conflicted coward who lacks any real confidence.