Export colours different to viewport colours

Several things to start with. First off, it looks like you may have HDR enabled in Windows? Turn that off.

Your original image does not have an embedded document profile (untagged). You say you don't understand color management, which is a problem right off because Photoshop revolves around it. You cannot avoid it, it's always there whether you want it or not. So you need a basic understanding. You always need to have an embedded color profile in the document. A color profile is sRGB, Adobe RGB, ProPhoto RGB or Image P3.This defines the colors.

Second, you need to understand that not all applications support color management. Of the native Windows applications most do, but a notable exception is Windows Explorer and the Windows desktop. This means that for a desktop image which this looks like, you need to prepare the image in the color space that is closest to your display's native behavior. There won't be any remapping, so it needs to match from the start. With color management, it doesn't need to match because it will be remapped.

Third, that's a very complex layer structure for someone new to Photoshop. Try to simplify. Before exporting, make a copy and flatten it first, then export. How does that look?

There's not enough information here to say anything conclusive, but those are a few places to start.