Every single webpage I've seen with webp / avif images also had autoplaying videos, intrusive ads, and megabytes of JS. I don't think jxl will change that... What's the point of introducing new image formats that are poorly supported and take longer to encode/decode if you're going to cancel out the space savings anyway?
I use JXL/AVIF/WEBP images on my website and don’t have videos, ads or unnecessary JavaScript.