I've never seen JPEG artifacts on images modified/saved 5 or fewer times. Viewing on a monitor including at 100%, printing photos, whatever - in practice the artifacts don't matter.

jpeg artifacts mainly show up on drawings. where they seriously degrade masking operations. which is a hobby of mine. so I always appreciate it when a drawing is a png. rather than a bunch of jpeg goop.

At high quality, the artifacts are not visible unless you take a magnifying glass to the pixels, which is a practice anathema to enjoying the photo.

I am referring to highly compressed images or low resolution ones, at high bitrates mostly all formats look the same.

what i mean is that jpeg squarish artifacts look ok while av1 angular artifacts look distorted

JPEG artifacts are less disturbing because they're so obviously artificial. WEBP and similar artifacts look more natural, which makes them harder to ignore.

I think I agree, low quality JPEGs give the idea of looking through slightly imperfect glass, WEBP and AV1 look a bit more like bad AI

For non-photographic images, I'm horribly sensible to the ringing artifacts. Thankfully, there's waifu2x (in denoise mode only) to remove those when textures don't confuse it too much and I use MozJPEG to encode, which really improves the result.

There's something to be said about this. A high quality JPEG after cleanup can sometimes be larger than an ARW (sony RAW) on export and it makes no sense to me.