They subtract 750 points from your REDEEMABLE XPER.
So that means you get to keep your points, but you can redeem the amount of XPER only once. Like, you have 30000 points for example, you feature a question, then you'll still have 30000 points but you'll be able to redeem only 29250 more. I'm pretty sure you get the logic by now.
It doesn't take away from your total or xper level, it just takes away from what you can spend. If you feature a question and you have 1000 xper points, you'll have 250 that you can spend, but you'll still have a total of 1000 and your level will stay the same. It doesn't affect the total that everyone else sees.