Perhaps your best course of action would be to consider the transaction with your father in 2019 to be a transfer with a retained life estate (i.e., your father quitclaimed the property to you and your siblings but retained the right to live there until his passing - you and your siblings would then have a remainder interest).
If the foregoing is the case, then your basis in the property would be the fair market value as of the date of your father's passing in 2019. You would need something on the order of a date of death appraisal for the property but your gain would be considerably reduced.
I understand that you have already sought legal counsel, but you should try to locate a local attorney or tax professional who is familiar with estate planning (trusts and estates).
See https://www.avvo.com/estate-planning-lawyer.html
See also https://taxexperts.naea.org/listing/service/estates-gifts-trusts
