I guess because Java it's more competitive than bedrock. Also, there are players that are just mean and toxic because it's their nature. I know sometimes it's kinda frustrating when someone, for example, kills you in Skywars with just a block or even without anything, but that's the trigger point. Those guys that can win, but they can't lose. They only have to win and win and, if they lose, they start being toxic, and not to say anything if they kill you after you killed them, they start saying: "hahaha you're so izi kid 10 hp... etcc". In a community, there's always nice people and toxic people, consequently you can't do anything about it.
Let me give you another example: In Tower Defence of Java, people who play it, are more nice and relax. They know how to work in team, and they aren't toxic by any ways ( there are exceptions of course). In this gamemode, people, in general, accepts a win or a defeat. Team skywars, it's a more competitive gamemode, so the majority of players can't handle a loss, and they only want to win. Eventually, they start being toxic or even insult people out of nowhere.
There will always be people like that, however, if they go more deep, you can report them for swearing at
https://www.cubecraft.net/forums/report-a-bedrock-player-or-bug.88/
It's the only way to relax this guys. And trust me because I have done it multiple times, and some of them stopped being toxic for a while.