Previously we could use --execute with the --throttle option in order to change the quota of an active reassignment. We seem to have lost this with KIP-455. The code has the following comment:
Seems like it was a mistake to change this because it breaks compatibility. We probably have to revert. At the same time, we can make the intent clearer both in the code and in the command help output.
(Edit: in KIP-455, we changed the behavior so that changes require quota changes require the --additional flag. So this issue is mostly about ensuring we have the integration testing to cover that behavior.)