This referendum is related to the reduction of existential deposit on Kusama's Asset Hub.
When you pay fees in sufficient assets, the system still calculates the base transaction fee in KSM. It converts it to the asset fee amount using the ratio of minimum balances. So:
fee_in_ksm * asset_min_balance / ksm_existential_deposit
So, if you reduce the KSM ED by a factor of 10, you also increase fees in sufficient assets by a factor of 10.
This proposal reduces the minimum balance requirement for all sufficient assets (USDT, RMRK, and DOT) by a factor of 10, preserving the ratio. There is also a fourth call to update the metadata for bridged DOT, since that failed when creating the asset due to the SafeCallFilter.
The enactment block (21,570,500) is set just before the Asset Hub would upgrade to the lower ED.