Why do I get 450 instead of 400 points sometimes?

It could mean that someone had deleted a giveaway worth 50P, so you get the points returned back to you.

Maybe you entered some giveaways and then :

• purchased a game or a bundle and after sync got the points back ?
• GA has been canceled and you got your points back ?

i think its because some giveaway that you entered was deleted after you reach 400 points

Thank you for the quick answers!