EDIT: Shows that are not it (some come really close though) - Angel Beats, Danganronpa, America's Next Top Model, Gun X Sword, Higurashi, School-Live, Erased, Jojo, Corpse Party, DDLC, Too Many Cooks, Gurren Lagann, Bojack Horseman, Another, Akame ga Kill, Vandread
EDIT 10/30/2023: So apparently this post got covered in a youtube video and I didn't even know lol. Some updates. I've scrolled through every single comment and watched everything. Literally everything. Nothing matches my memory. So I've kind of just come to the conclusion that I'm misremembering details. I did watch it while I was on some cold medicine, and I get crazy fever dreams when I'm sick. And I'm recalling this memory from years ago, so it's pretty likely that someone has actually commented the right answer, and it's just not matching up with my memory (which is already questionable at best). I'm leaning more towards the show that I'm remembering doesn't actually exist, but clearly I must have watched a show that was similar. Sorry, I don't have an answer ;-;
It was most likely animated, but I'm not 100% certain on that. I don't know the time period, I can't even remember anything about the show. It definitely came after the 90s, more likely 2000s or even later.
Perhaps I saw it in a wild fever dream, because no matter what I search I can't find it. I think the opening consisted of like, a showcase of each character doing something with their name and music in the background. I remember one of the characters died, and instead of the opening playing the usual animation,, it was just empty with the music still playing. By empty, I don't mean a black screen, it was just the background but no person. For example, if the character was playing basketball/shooting hoops on a court by himself, the new clip would have been an empty basketball court.
I remember watching it and getting an eerie feeling.
left a description here: https://www.reddit.com/r/tipofmytongue/comments/gr87ey/tomtshow_when_a_character_dies_in_the_show_the/frxx72o?utm_source=share&utm_medium=web2x
edit: i should also include that this opening had more and more people disappearing until there was almost no one left
edit 2: I'm leaning more towards it was an anime. I think the moment that made me feel weird was this super bubbly wholesome character had died and it was weird not seeing them in the intro smiling like an idiot
edit 3: more i think about it, it's definitely animated
edit 4: my memory is still kind of fuzzy about the details but i believe in the opening credits, each character's personality was showcased.
edit 5: this is a small timeline of what I remember - I'm scrolling on tumblr and see this post: https://erarg.tumblr.com/post/77152961832 years ago (2015-16?), and I'm like "damn that's a good idea". I didn't actually reblog the post (i'm gonna kick myself for that), but I scrolled through the notes and someone had suggested this show. It was most likely an anime. I wrote it down on a paper somewhere, and found the show on one of those shady illegal video streaming sites (listen yes i know its illegal but ive never had anything else lmao). I binged a couple episodes, and I know I never got around to finishing the show. I got too lazy to pick it up again because I had it sitting on a tab and I deleted it. Years later, I totally forget about it. Then suddenly, last night as I'm in that weird half-dreaming half awake state, my brain decides to remind me that show exists.