Hestia Background image with very low quality and don't roll when scroll down

Hello friends, I need a very urgent help that I’ve done everything but I can’t solve it. As you can see on my website on the main page, the background image doesn’t move along the scroll down and it also lost a lot of quality. At first it worked well but it has been a month since it stopped working and I’ve done everything to solve it but I can’t find anything, I’ve looked everywhere. I really appreciate you helping me.

My site is: Sinutafce.pt

I have already disabled all the plug ins and enabled to see if it was conflict but no.

We are not the developers of the hestia theme. Ask them…