How to detect when player rejoin on singleplayer world

[fathom shell]

I asked chat gpt how to do it and he said that there is custom:game_leave scoreboard or something like this but im not sure if he is telling the truth and i cant check directly in minecraft right now 🙁

[fathom shell]

Thats why i asked here

[naive oxide]

When player joins singleplayer mode load function is being run

[fathom shell]

Rlly?

Ok thanks