It very much sounds like System of a Down. And I was forced to listen to that band ad nauseum when I was a child, so I'd know. lol.. It also seems to take some inspiration from 80s thrash metal. To be honest though Linkin Park, KoRn, and other bands are considered to be metal [by some] and this sounds to be harder than likin park, so...
One thing that suggests its metal is that fact that the lyrical matter matches that of typical heavy metal lyrics. Not about love and typical subjects, but rather about society, fantastical themes, tragedy, death, et cetera. . . and I just realized you were talking about bursters when saying they are not metal. lmao...
I did listen to Bursters and can wholeheartedly agree they are not metal. Wikipedia places them as metalcore. I listened to their singles and they seem pop act with rock influences. I'd say Day6 is harder than them, but wouldn't say day6 is metalcore, so... but there is a ongoing heated debate and metalcore and metal and I kinda don't want to go into that, so... But I have noticed that bands that are metalcore or hard rock may be lumped in with metal depending on the streaming platform. As these platforms are typically run by big suits who probably don't have respect for the intricacies differentiating music genres, I am not surprised that Bursters would be considered metal. lol..
Uh.. I have gone on for too long.. Can longer posts count as 2 or 3 posts for the daily requirements
tagging
@RandAlThor because I know he has varried interest in music that likely stretches back to include classic metal (e.g., Sabbath, Maiden, Dio, Priest) and Thrash (e.g., Testament, Exodus, Metallica, Megadeth, Anthrax, Slayer) and could give a nuanced opinion... and
@Yachii because she is obviously more of a metal fan these days than she is a k-pop.