Doesn't look like this came from the tweet, which means it ought to have a different source.
While this doesn't seem against the rules, is it something that is ok to keep doing or frowned upon? Seen it happen on other posts under this artist before.
While this doesn't seem against the rules, is it something that is ok to keep doing or frowned upon? Seen it happen on other posts under this artist before.
I'd presume it depends on why this isn't the correct source. If the user somehow got ahold of the original file before Twitter compressed it from the artist themselves over Discord or something and has permission, but there's nowhere on the web you could actually link to as a source, I doubt there's a problem. If this was found somewhere else like Pixiv, but then the lower-quality Twitter version is linked as the source instead, it's somewhat frowned upon, since you should just link the right source. If it's something like a paid reward that you're trying to get around the ban on paid rewards by lying about the source, it's very frowned on.
Technically in the case that the source is unlinkable, the source field should be filled in with words describing where you got the image from. It doesn't have to be a URL.