If you don’t claim earnings before 100 rounds pass do you lose those earnings?
No, you don’t lose them. They’ll continue to accrue.
The only thing that happens if you wait longer than 100 rounds is that you will have to submit an additional transaction in order to claim all your earnings. If you wait 200+ rounds you’ll need 3 transactions, 300+ rounds you’ll need 4 transactions, etc. There’s no lost earnings.