Possibly silly question, but what level are you currently? The maximum level is 12 and after that what you're seeing would be expected, though the current experience would be in the region of 97K rather than 9K.
Yeah, I guess you were right

I'm at Level 12 for my characters. About 53,000 XP for each.
Seems weird to me to have a hard cap at Level 12. No more "level-up" screens, HP additions, spell slots opening up, or STR/DEX/CON/INT/WIS/CHA things to get?
I was already bummed Larian chose not to do an expansion or anything. Adding more levels, spells, and spell slots would've been pretty cool, though. It feels a little unfinished to cap leveling at "12", imo. I'm okay with them focusing on other ideas/games, but leveling seems unfinished. I can't remember the last game I've played that stops leveling so early. That said, I'm impressed by the number of spells and such there actually are. I just wish I could level up a bit more to more easily take advantage of more of that depth and breadth while playing through the game
I've probably played at least 100 hours since I last leveled up, shortly before or after reaching Act III, and I haven't beaten the game yet. That's a lot of campaign gaming -- 44,000 XP in my case so far -- where you're just coasting along with the same abilities and only able to have one Level VI spell casting slot during combat, for example. I have several side quests and main quests to go yet.
Gale, Shadowheart, and Jaheira each also still have eight empty/unusable slots when I look at their spell books (hotkey "k")
If the game will be permanently capped at Level 12, I think they should at least have better messaging to the player so it doesn't look like a bug. I've been playing a month thinking it was a bug because the UI/UX is unclear (not intuitive) regarding this. The character XP bars are blank, too. Maybe some, "Max Reached" messaging somehow would be nice. Their customer support seemed to think it was a bug, so I wasn't alone. (Who knows, though, maybe we'll find out in a future patch that Levels 13+ open up and it actually was a bug.)