Hello,
In order to reduce confusion within iGP Manager, league hosts have to counteract DST changes by changing their race time (at least 24 hours before the next race).
"
If your clock moves +1, then your race is +1 on the clock, and if your clock moves -1, then your race is -1 on the clock. League hosts can adjust the schedule in advance if they wish to avoid this."¹
The reason iGP Manager doesn't change the time automatically is that not all countries change their timezones at the same time - and some countries don't change at all.
As a host, to counteract the DST changes, you can change the race time in the opposite direction; for example, if the clocks are going backwards, you have to put your race time 1 hour forwards and vice versa. Of course, this is depending on whether your league wants to race at the same time, or with a 1 hour change - which could depend on where your managers are based.
¹ -
Daylight Saving Times announcement
Community Manager