If you incorrectly estimate your AGI for ACA do you lose the entire subsidy?

I assume you mean 'projected' (past tense); in 2025 it is no longer possible to make projections for the enrollment period in late 2023.

You can receive PTC below the normal lower limit of 100% FPL household modified AGI (which I assume your 14500 'AGI' is) IF you (or a household member) enrolled through the government marketplace AND received APTC (what you call subsidy) based on incorrect information -- UNLESS you provided that information "with intentional or reckless disregard for the facts", which based on your description you didn't. See instructions for form 8962 line 5 and (as instructed) pub 974 definition of applicable taxpayer. Whether TurboTax analyzed this correctly (and how) or just guessed, I don't know.

If you had projected 3k the marketplace would NOT have found you eligible for APTC, and you would not now qualify for this exception. It might have found you eligible for Medicaid; that is supposed to be integrated (i.e. applying for APTC is automatically considered an application for Medicaid -- or SCHIP -- as a possible alternative) but how it works for FL in particular I don't know.

This has not changed recently, although the hard upper limit of 400% FPL was removed by ARPA in 2021; the affordability phaseout remains in place, and provides an effective but somewhat variable upper limit.