For clarity, It's not a "Photoshop" issue, it's an image processing issue. Or that the sizing and file format has changed a few times. The image below was edited in Photoshop. No graininess or noise there. This is a jpeg file converted from a tiff file.
If by Processing you mean... Enhancing/Denoising - then yes, you can put it like that.
.jpg is not a lossless format. But it's still a "digital" image format - which can be subjected to changes/enhancements. Especially this days (well, for quite some time now - since in 2024 even A.I. has a big saying in this regard) - when every capable image editing software (Photoshop - does qualify, be it Lightroom Classic or its big brother) - has an arsenal of image auto-enhancing tools. The image is also down-scalled to
1920x1290 - which tends to heavilly diminish the noise level - compared to its original resolution of at least
4128 x 2752. And then there's the image
procesing....
Not to mention you shot above image with a Nikon D850, which sure... it's a DSLR from 2017 - so a bit far from the latest and the greatest. But's it's still a full frame camera (low-noise performance - since the sensor can capture more light - compared to smaller formats) - quite capable even for 2024 and still used by some professionals. Furthermore, that image has enough light for a low ISO of 1000 to be used - so the noise level should be quite minimal. Same image shot with a phone - you'd have a lot of internal cheating/enhancing - to get same level of noise.
So, yeah... even .jpg images looks great - if the conditions in which the imake was taken (or created) - are that faborable. On the other hand - if the image was taken with a midrange smarthphone and the light was not quite ideal, the.... procesed image in Photshop - is sure to look better than the original/source. That's not to say - that Photshop is an issue, quite the oppsite - it's a solution... After all, in this day and age "fake details" - is what image processing is mainly about. Thus, an iPhone 15 with its tiny senzor - can compete even with a full frame profesional camera - due to "image processing". Well, not if it's using a Telephoto Lenses and the subject of photograhy is wildlife. Not yet - at least, cause in the near future - A.i. might be able to fake that too. Imagine someone who never took a decent photo in his life - yet, using a modern A.I. text to image generator in his browser - he might achieve better results than a profesional with 20.000$ Photo Gear.
