There’s basically zero disadvantage to turning on DLSS 2. Most of the time you cannot or can barely tell the difference.
DLSS 3 introduces lots of artifacting, some frames straight up look like DALL-E image, it adds input lag, and it needs you to already have a high framerate to start with to make it bearable, text in particular gets mangled by it.
Fast paced games and games that rely on quick reactions are a no-go for DLSS 3. It’s suitable for games like MS flight sim where adding input lag doesn’t really matter and there’s not rapid movement.