SPBB CSS fix for all Mobile Devices:
@media screen and (max-width: 820px) {
#sp-page-builder .page-content .sppb-section,
#sp-page-builder .sppb-section,
.mod-sppagebuilder .sppb-section {background-attachment: scroll !important;}
}
SPPB documenation tip: https://www.joomshaper.com/documentation/sp-page-builder/troubleshooting#background-image-in-section-is-resized-on-safari-mobile-browser
Yes, you can modify that for iPhones browsers only.
/* --- iPhone 6+, 7+ and 8+ --- */
@media only screen
and (min-device-width: 375px)
and (max-device-width: 736px)
and (-webkit-min-device-pixel-ratio: 3) {
#sp-page-builder .page-content .sppb-section,
#sp-page-builder .sppb-section,
.mod-sppagebuilder .sppb-section {background-attachment: scroll !important;}
}