Sometimes you might realize that you are going to end a match turn 3 and not get the XP you earned. This error is not very common, but when it occurs it is not very pleasant, especially when you are about to level up. Unfortunately, there doesn’t seem to be a permanent solution to this problem right now, but there is a way to avoid it.
How to fix no XP after match in Splatoon 3
We’ve only been affected once by the XP glitch in Splatoon 3. We ended a match on the hour, when the cards were changing. Unfortunately, the map update announcement seems to have an opportunity to overwrite your post-game stats if things line up just right. In this case, you will not receive XP or other rewards for completing a game.
The only way to completely avoid the XP error is to not start a game about three minutes before the scheduled map change. Then you don’t have to worry about the announcement foreshadowing your game results.
Since this can only happen hourly, you shouldn’t be affected by it too often. It’s frustrating for sure, but relatively benign as far as bugs go. We wouldn’t be surprised if it gets patched up quickly.
https://www.gamerevolution.com/guides/714576-splatoon-3-not-getting-xp-after-match-bug-fix Splatoon 3: XP not received after match bug fix