Deceased mother owes taxes to CA & IRS (no estate; house in joint survivorship)

I am sorry if this has been covered. I do find a lot of similar stories but not quite the one I am looking for… so, here it is:

1. My mother and I bought a house in 2018 w/ joint tenancy with survivorship. It's been rented out since 2019.
2. My mother got all monies related to the rental.
3. My mother died in July.
4. My mother had not paid her 2024 taxes. She also did not withhold tax from her retirement income.
5. I have never filed joint income taxes or anything of the like with her.
6. There is no estate; I was advised not to file for probate. There is, simply put, nothing there (no life insurance, no 401k). She got CalSTRS, SSI, and rental income. She has a car worth, at best, $1.2k.
7. Her executors died before she did. I am named second trustee in a 2010 trust I found.
8. All her bank accounts were POD'ed to others; her CalSTRS beneficiary went to someone else.
9. I filed her taxes with HR Block expecting some guidance. I got "I think" or "I'm not sure" in response; I realize it's an uncommon situation.
10. After five hours of hold time, the IRS deigned to give me three minutes of time to tell me to file Form 56. The form says I take fiduciary responsibility. I most certainly do not.
11. Both the CA FTB and IRS sent me bills with penalties and interest.

This is not a small sum of money to me (totaling ~$16k between the two). I know I'm going to get hit again in 2025. My biggest problem is estate lawyers, property lawyers, and probate lawyers keep ping ponging me between each other saying it's not their area of expertise.

My questions are:
Do I have to pay the IRS and CA FTB?
Does the IRS and CA FTB have rights to put a lien against the house?
Can either party try to seize the house if I do not have the funds to pay?
Am I allowed to argue down the amount owed if they determine I must pay?
I see some form about spouses asking for clemency from their spouse's taxes. Could that not apply here?