Is this a Bug? (Aswered)

Why do you expect xp for a won game?

Its the other way round.
You make a giveaway for others and then you get 'exp'. And then you power up after every level ;)
https://www.steamgifts.com/about/faq

View attached image.

If you mean Contributor Value by "exp", then no, it's not a bug, it's a feature. You gain CV by giving away games, not winning them. The incentive is there for you to give back, not to win more.

Am just wondering if they give exp for every game or certain games (or certain events if there is events)

Edit: they give you exp if you giveaway a game (ty to raggart cultofpersonalitea and blackface for telling me how it works)

https://www.steamgifts.com/about/faq

Check out "Contributor Levels"