New camera

Hey all, I'm looking for a new camera for birding. I have a nikon p900 but which is absolutely brilliant for taking pics of the moon and I love it but it doesn't take the best quality pictures of birds. It's okay if you're very close and don't need to zoom much at all, or if the lighting is just right, but otherwise they all seem to lose focus and be blurry / lesser quality. What do you all recommend? There are some incredible shots in here. My budget is around 1/1.5k with some intense saving up lol, but just need a rough place to start.

Also side note if anyone takes pics of mushrooms like close up macro ones, what are you using?

Thanks in advance and happy birding!! :)