I've watched it all with interest. Like others, and most people I know, I loved their wedding, and loved seeing Harry so happy. He was very popular. It looked like Meghan was welcomed in very nicely from the unemotional royal family.
Then they changed from being a popular couple, but entirely due to their actions.
They're very typical of a couple I know who are always putting down people they know won't answer back, but if anyone pulls them up on it, they're immediately the victims. Most people recognise that they are doing this to stop repercussion from their bullying behaviour, but it's always surprising how many people fall for the victim narrative even when they've seen their behaviour elsewhere, and start excusing it.
I think the only way they could pull this back now is to do nothing large for the next year. Keep quiet, not court the press, do some charitable things and not say anything negative or ask their pet press people to say negative things. The only thing to say connected to the royal family would be positive things like birthday greetings etc. If anything negative comes out from "royal experts" a bland denial, but not engaging at all.
Then this time next year, they could ask for a Christmas visit, and gradually do a few things with the royal family, but being careful not to say anything negative at all.
With that they may come back into the fold and their popularity would probably go up again, although I doubt to the level it once was.