The Netflix show isn't anime. It's a live-action adaptation of a manga. Apparently it's a fairly faithful adaptation.

As for the flashbacks and soliloquy, I didn't think it was that excessive. Each flashback is like a minute (or less) long and explains something about a character. Shows generally benefit from a "show, don't tell" approach to character-building. Idk how else you're supposed to learn a character's backstory without either a flashback or a character just explaining "this is what I used to do," which would get real boring real quick if everyone just did that.

Admittedly, some flashbacks get reused though, which is pretty annoying ngl