The drop in both USD and SHARE is most likely due to the fact that on positive rebase SHARE are automatically burnt when moved to create USD. Depending on the TWAP this can lead to a loss. It is also quite complex to understand.
This proposal is to send 100% of the newly minted USD to the Treasury so they will be sold for ETH. This ensure that new USDs are put in the system (currently they aren't even if the USD price is 70 cents). The ETH in the Treasury will be used to avoid going back to a USD price so low as the Treasury use its reserve to buy USD.
When there will be too much of excess of ETH, we will use it to buy and burn some SHARE tokens.
The ETH in the Treasury is the property of SHARE holders so nothing is lost.
You can find more details here => https://gov.dollarprotocol.com/t/proposal-set-the-treasury-to-100/97/6