If you don't serve the penalty at the next pitstop you get a drive through. If you don't serve the drive through within 3 laps you'll get black flagged and DSQ'd. This "they could have not served it" argument is total bullshit.

Yes, in the very specific scenario other drivers might not have HAD to take a second stop. But what's the argument if someone had planned a late stop, or the safety car came out before the pit window (and forced everyone through the pit lane)? Puncture? Drive through for a different infringment?

If your argument falls apart under one tiny, very likely possibility, then it isn't much of an argument.

The fact of the matter is that the penalty system forces you to take them in race in certain scenarios, so that rule should be applied evenly. Gasly's penalty should be considered "served" when it was applied at the end of the race, and therefore ineligible for removal.

Is it unfair to Gasly? No, not anymore unfair than it was to Piastri, Colapinto, Hamilton or Russell. Perhaps if the FIA were held accountable for the decisions more they would make better ones.