Replacing is bad since 3d printed parts aren't very air tight. Now if they were the ones that go over the original it would actually be more funny than infuriating.
I don’t think valve stem caps keep air in. I think they simply stop dirt from getting into the valve stem which could cause it to become non functional or the valve to stick open on the tire to deflate
The ones with the rubber seals keep air in. A lot of new cars have those and a lot of cars with tire pressure sensors require them. Regular covers without the seal don't keep air in obviously but I still wouldn't trust the ones 3d printed by a random person because I don't know what their QC is. The ones that go over original covers are the best either way.
I can guarantee the original caps aren't airtight either. That's not what they're designed for. The valve is designed to be airtight. The cap only stops dust building up.
A good cap will keep a decent amount of air in and protect the valve from damage. I wouldn't trust a 3d printed cap that I don't know who made and how good their QC is. If I made it myself though I'd be less hesitant. Either way, it's better to 3d print covers that go over the originals.
For future reference, the extra stuff is everything after the question mark. It's not always bad stuff; the question mark is for a bunch of queries, including links to specific time stamps on YouTube videos. Adding ?t=42 to the end of a clean YouTube link will start the video at 42 seconds as an example: https://youtu.be/dQw4w9WgXcQ?t=42
Although these "query strings" are sometimes useful, most of the time, they're just for tracking purposes and can be removed with no issue. "If you don't know what it does, it's probably not needed" is a good rule of thumb