Lock background image so it won't moving upon scrolling on mobile

Site URL: https://www.arbala.co.uk/shop

Hello, I would like to find css that locks/freezes the background image so it doesn't move when scrolling on my mobile site. This is the code I used which works for my desktop site:

(I would like this to be applied to only my shop page)

section[data-section-id="6033d77c74fab235129fb8f8"] .section-background {
    background: url('https://static1.squarespace.com/static/6033d6addf0e7479ebf57add/t/60452f9c2219a52fe71d54fb/1615146916345/2Arbala+Gradients.png');
    background-size: cover;
  background-position: center;
  background-attachment: fixed;
  background-repeat: no-repeat;
}

password for site: Ghillie5

https://www.arbala.co.uk/shop

I'd really appreciate anyones help!! Thank you!