I think a lot of people have lost faith in the ability of the world to come all together and make the necessary sacrifices to make a difference. Especially when some parts of the world are in competition with each other and not making these sacrifices allows them an edge.
Also another group of people have realized they are not willing to forgo all their petty and unnecessary comforts nor are they willing to pay any price increases that would be required to adopt less economical but more sustainable services or production methods.
I don't think there's been any big change in climate change believers/deniers, but i do think some people have started accepting that we're doomed and that there is no "practical" solution. And if you think you're doomed, you might as well skip the sacrifices and enjoy your last days (decades) to the fullest.
Its not that.
Basically, on the average, people don't have ability to think rationally into the future. Most people think only 1 level of cause and effect.
Right now, for the vast majority of people, global warming isn't a problem when your house has AC, your car has AC, your workplace has AC. When you are forced to do things that you see no direct effect of, it makes it seem less important, and its a self reinforcing cycle where you see other people not doing it and you wonder why you have to make your life harder.
People will start caring only when their direct lives are affected. So unfortunately, the only way to fix global warming is to let it get bad enough to where there is enough death and destruction for people to start paying attention.
"People aren't willing to pay price increases" is interesting. Of course that's what they say when you ask them directly. Yet everyone is currently paying massive price increases as a result of covid-era money printing. I'm not saying you're wrong necessarily but what it shows it that it has been possible in very recent times that a collecive decision was made which increased general prices for everyone.
> that a collecive decision was made which increased general prices for everyone
I think you're referring to inflation with that? I wouldn't necessarily say that inflation is the result of a "decision", certainly not a direct decision of any single person nor any collective group. Economies can move around in weird and unpredictable ways, and they are also quite intertwined at the global level making policy decisions even more complicated and unpredictable.
The "money printing" decision wasn't made by asking the public: "would you like to help our economy and businesses and our essential public services in this tragic event? Oh btw you'll be paying for all of this with inflation, are you still sure?". Politicians tend to conveniently leave the second part out, and also, this questions wasn't asked to the public at all. I believe a sizeable amount of the public would've responded "no, let the people die, let the businesses die, i'm not paying for them".
Which is why for example, in many democracies with tools of direct democracy, such tools cannot affect fiscal policy, because people are dumb and they would just say "i want all of the welfare and zero of the taxes", bringing the country to ruin.
People are largely unaware of the sources of those price increases, at least in the US, which is why they were such a successful bludgeon in recent elections.