In case my opinion's worth anything: I dislike tags-as-sections, I prefer tags and sections, the way Pixelation currently has it. Just feels more organized and intuitive to me, even if similar results can be achieved with both.

I personally rather like the forum format for critique, and don't want to scroll through a page full of posts or verbose threads a la image boards or Mastodon. I think the only thing that's really missing is the ability to quickly preview the art in the thread, to see what sort of art it is and whether there have been updated by the OP. A small (for compactness and easy scrolling) thumbnail that can be hovered-over or tapped (touchscreens) to see a (slightly) larger version of either the first or latest image posted by the OP (or better yet, both!) next to the thread in the thread list would be a great addition to the current format.

It looks rather odd to me that the shadows on the character are lighter than the environment, which is more likely to be lit by ambient light.

How about switching the dark brown with the black? As a bonus, that'll give you increased contrast on the character and reduced contrast in the background, making the character pop more.
Here's an edit doing that:

I also:
- replaced the dark brown on the mountains and darkest red on the moon with grey from the castle to help the colours transition better, and reducing your colour count as a bonus
- made the hand on the sword's handle a little larger, it was rather small. That whole arm feels rather short though, so you may want to work on that. If it's meant to be foreshortened, you'll need to clarify that.
- added some extra transitions/detail using the dark brown from the new "background". Switching the colours around leaves you more room for that :]

The IMG tag requires an image URL, but you're using the URLs of the webpages the images are on. The web browser doesn't know how to interpret a webpage as an image, which is why it doesn't work.
Wrong: https://imgur.com/a/xiOH2yT (note the /a/ album URL signifier, and lack of file extension)
Right: https://i.imgur.com/hEKtM1m.gif (note the file extension)
You can get the URLs by right-clicking on the image and selecting "Copy Image Location" or "Copy Image Address". You could also click the image in your account's full list of images, that should pop up a thing with many sharing options, BBCode and direct link URLs included.

Glad you found it useful!

Some additional notes:
Thick moustaches usually don't have that much space between them and the nose. There's some distance, but usually not a pixel's worth at this size. I left that pixel distance in my edit because I wanted to keep the changes to the nose clear and obvious, and then forgot to mention it.
Having the hair colour run straight into the skin looks rather harsh. You can use lighter colours to ease the transition and make it look like there are some thinner/less-numerous hairs there. I did that in my edit, using the darker skin colours.
With the hair, the main change was adding indication of where the hair's coming from - the part, and the growth at the edge above the forehead. It looks like you got this, but I wanted to make sure you understand for your future works.
The eyes are a bit hard to see. Some darker colours to highlight the shape of the skin around them would help. I did a little of this in my edit, but didn't take it far enough.