In what ways does it look that way, if you recall?
I hear this semi-often, but I don't really get it. The base UI of Discord is pretty normal / looks just like every other chat app out there. Is it the ads for nitro and stuff like that were the issue?
Animated server logos, colorful /gradient and tonally-varied usernames & avatars, the super emoji or whatever they're called, etc all feel like they're pushing more towards Twitch chat than anything else. Which as another commenter remarked, is essentially aligned with their original and biggest target demographic.
It’s also their method of making money which is locking cosmetics behind subscription or purchases.
Other option would be to limit core features for non paying users.
I like those things tbh. A lot of it helps make things more visually interesting, and other users more distinctive.
I think the base UI of Discord is fine, but having used it for almost a decade at this point, the UI has gotten worse. Besides the ads you've mentioned, they've added a lot more clutter (random icons, rarely used features, hidden menus, etc.). When I look at screenshots from 2019, I weep.