Whilst moved is the correct word, you may not understand it in the context.
It is not constrained to a specific printer. Please, do not panic, you gain, you do not lose.
I will reword it so it makes more sense.
In the screenshot above you can see Other topics & Share your prints, they are the category.
You chose the category Makerworld.
I changed the category from Makerworld to Other topics > Share your prints.
I did this because that is exactly what the topic is about, you wrote a post with the express aim (based entirely on your own words) to show the MW community about something you have made. Sharing is good and welcomed.
Assigning it to the general Makerword category means it will not be found when anyone looks through other models users have shared when they go through the Other topics > Share your prints category specifically.
Your post does not get hidden, it is on the identical list all other posts appear on.
It gains something. Did you know you can click on the category name on posts?
When you do that, you see all the posts within that category.
For illustration only, think of the forum as a giant filing cabinet. This filing cabinet contains every post ever written. On the outside of the filing cabinet is an always updating list of the most recently changed files. This is excellent when something is new and fresh as it means you can spot something of interest and grab that file (post).
After time passes, the post hasn’t been updated and it is so far down that list it will not easily be found.
Along comes someone who wants to see all the files (posts) that contain examples of the designs other people have shared.
You put yours in the massive Makerworld section, which contains a significant number of files (posts) that have nothing to do with promoting your work, that person is looking in the section specifically for promoting work and they see them all, except yours as they didn’t even consider it would not be filed in the correct location.