Solved

qual on inters, start on slick

What did you try to do?
changeable english weather. most qualyd on inters. opened up race through league shortcut...

What happened instead?
..most drivers still on inters. without closing the window.. suddenly all were on slicks...another manager noticed this. new feature (the rain has stopped, i guess in real life they can change tired) or bug?

Did the bug happen in the app, on PC, or both?
PC

What operating system is your PC?
windows 10

Which browser did you experience the problem in?
firefox

Can the bug be reproduced?
not sure

If you read the announcements you will find recently there was an update that allows the AI to choose which tyres to be on pre-race up to a minute before lights out. This is to stop people starting on the wrong tyres as the race starts.

This is all intended and the advanced race strategy is followed.