This stuff is a mess due to lack of communication from CoveredCA and inscrutable forms... However, complaining about having to pay back subsidies to CA is not fair.
What I see in my case is that I got CA subsidy ("premium assistance subsidy", form 3895 part II column C) for a part of the premium for jan-apr. Then I got Fed subsidy for essentially the full premium ("premium tax credit", form 1095-A, part II column C) for may through dec. This PAS and PTC is money CA respectively the feds paid to the insurance for me, so it's money I already "got".
What happens now is that, as previously mentioned in this thread, the federal subsidy is retroactive to january. In my case, I am eligible for a total federal PTC in 2021 of ~$20k (in turbotax look at form 8962 line 24) and I actually got ~16k (may-dec. see line 25 in form 8962) so I am eligible for another $4k (line 26), which turbotax "gets for me" in the form of a tax credit (see sched 3).
On the California return, due to the Fed paying for so much of the premium I am no longer eligible for california subsidy, so they want their money back (can't really complain about that), which turns out to be ~$3k. This means that effectively I am shuttling $3k from the IRS to the FTB and pocket another $1k in tax credit in the process. I am really upset about the hour+ it has taken me to track all this down, but overall given that I'm $1k ahead it's not the end of the world.
Now in addition to sorting all this out, my insurance (BlueShield) withdrew the "premium minus CA subsidy" amount from my account for jan-may 2021, i.e., they over-withdrew one month. So at first I thought I had to complain to get reimbursed until I figured out they finally applied the credit to jan-feb 2022.
Not looking forward to what all this nets out for TY 2022...
