Images saved in Preview appear washed-out on the web

How do I prevent images looking washed-out after manipulation in Preview?

After I do anything to an image (crop, adjust size, levels, ...), and save the result it looks ok on a Mac, but washed-out on web. Also, very similar question got quelched some time ago (https://discussions.apple.com/thread/256030181?), without any useful answer or result.

After some experimenting, it appears that we need to Assign a profile before saving an image! By default a profile produces washed-out JPEGs, but selecting "Generic RGB profile" before saving an image helps a lot.

Here is an example without selecting "Generic RGB profile".

Here is how it looks like if generic profile is selected before saving.