Solved

Tyre stint issue?

This happens if the pits of a team are located before the finish line. After leaving the pits the car crosses the finish line in the pit lane and gets already a lap added even though it just drove a few meters. For own cars you can also see this in your drivers lap by lap report: For the last lap of a stint before pitting the report already lists the full fuel amount from the pit stop and fresh tyres. If  another car pitting at the same time has its pits after the finish line, where most are located, then it isn't affected by this and shows the correct amount of laps and thus one lap less. 

As Rik wrote, click on the past race you want the details for and then on the Finish time of any driver you want to check out to get his lap by lap report. Only for own drivers, at least with desktop browser, you see remaining fuel after every lap and tyre condition. I'm not sure if all of this is present in the App or mobile web version, some of that information might be cut for screen size reasons. So maybe you'll have to use the browser version for that and if you use a mobile device you probably have to set up the browser in its options to show the desktop/full version of websites.