What is the Tax rule for "constructive sale/straddle treatment" of futures on SPY

I have continuously owned SPY (and other S&P 500 ETFs) since 2006 as long-term investments.

I'm considering adding a separate strategy where I occasionally short ES futures **only during regular market hours (9:30 AM–4:00 PM ET)** and close the futures position near the market close the same day. My long SPY position would remain unchanged and fully invested at all times.

Would this create any issues under the **constructive sale rules** or the **tax straddle rules**? Not asking for trading advice - just being prudent.

More specifically, could this cause the IRS to treat any portion of my **unrealized gains** in SPY as taxable, even though I have not sold my SPY holdings?

Thanks very much!