quality issues help

• You have noise in the image
• upsizing cause aliasing around the cup.
• there are inconsitances in the image, like this: 

   

The overall size in pixels and the megabytes are not useful quality indicators, except that a 5k image probably means that you upsized the image a lot. sRGB is a requirement for Adobe stock, but I never saw an image getting refused for violating this requirement. But yes, it is good to follow up with this.

It's more likely not about the size, but rather the lighting, composition, or realism, which probably didn't meet their quality standards.

Hello,

This may or may not be a consideration, but the background with the blurred lights as round dots are somewhat distracting.

 I think the steam from the cup is okay, as one wants to give the impression of a hot cup of chocolate, especially with the marshmallows on top. Do something else with the background.

Some minor cleanup as noted. Avoid the default AI square format. Give the buyer room to crop or add copy as desired.