How do I know what causes Layout shifts?

Hello, I’m trying to improve my pagespeed for my product pages, example URL: Vela Cuban Anklet – Elegant Titanium Steel Geometric Women’s Bracelet – InteriorGlows. And I went to Performance to check what causes the Layout Shift and I see 4 elements, but I still do not know what causes it. Can someone please help me with this?

Try removing your pop-ups

This one is probably causes by your logo image loading and making your header grow higher.
Try adding this code to, say, “Custom CSS” of the header section and see if it helps:

.header__heading-logo-wrapper {
  min-height: 50px;
}

Also – you have a bunch of things like this, which needs to be fixed – I’d probably reach out to Blockly for support on this: