Sport Mode: Why Did My Finishing Position Fall After the Race When I Didn't Get a Penalty?

It's because you didn't use the mandatory/required tyres.

In many Sport Mode races, specifically the FIA Online Championship Nations Cup and Manufacturer Series races, and some of the Daily Race C events, there is a mandatory/required tyre: a tyre, or tyres, that you are required to use during the race.

All events have maximum and minimum tyre ratings, but only some have required tyres too. It may be that just one tyre grade is required, or sometimes two, and occasionally all three, and they may be different from the tyres you are permitted to use (though they will fall in the range allowed).

For example, a race may have a minimum tyre of Racing Hards and a maximum tyre of Racing Softs. That means that you can use all three main grades of Racing tyre - hard, medium, soft - during the race as you see fit. However it may also have a required tyre of Racing Hards. That means that you must use Racing Hard tyres at least once in the course of the race. You still have free rein over your tyre strategy, but it must include the required tyre for at least one lap.

Required tyres are displayed in two places before you race. The first is both in-game and on the game's website in the "Race Details" screen before you even enter the race:



The required tyres for the above race are Racing Hard and Racing Medium. This means that you must drive at least one lap on Racing Hard, and at least one lap on Racing Medium tyres during the race, so you must make at least one pit stop to change from one to the other.

This information also appears again in the pre-race lobby:



The required tyres for the above race are Racing Hard. This means that you must drive at least one lap on Racing Hard tyres during the race.

If you do not use the required tyres, you will receive a post-race penalty. As of the start of the 2020 FIA Series this weekend, that penalty is 60 seconds in all FIA races. In Daily Races with required tyres it is a 20-second penalty.

The game applies the penalty to any offending player the moment they finish the race. If you have such a penalty you may start to fall down the order as cars that do not have the penalty finish behind you and beat your overall race finish time with the penalty included. Conversely, if you don't have a penalty you may leap ahead of cars that do, so long as you are finishing ahead of their overall race finish time with the penalty included.