As the title suggests, Indexers are currently able to change the reward rates for delegators before paying out. If an Indexer wants to change the reward rate for their Delegators they should first have to pay out all currently accumulated rewards.
This was already proposed in another thread and here was the explanation behind why this won’t be possible, at least not in the way it’s suggested:
Also, same suggestion was posted here as well: Indexers should have to payout All outstanding rewards Before they are allowed to change fee rates
You are absolutely right