Great question. If your Shopify Payments account has a hold/reserve placed on it, then you can navigate to Settings/Payment Providers/View Payouts/Transactions:
Under the "transaction type," you should see the "reserved funds," which will indicate how much of an order was reserved. If you go back one screen, you should see a "balance" field, which should indicate the told amount to be paid out, which I believe includes reserve funds. Though, you can also add the 90 days to the day the funds were placed in reserve to determine the payout date.
Let me know if you have any questions!