I think it may be because people are fading in and out of deviantart. The summer might be a better time to sell. More people online and more money to spend on ridiculous things.
Not to mention, many people have sorta move away from deviantart. While it's still popular, I think artists have made themselves more available on other sites as well. Patreon has also gained a lot of interest for artists wanting to make money. i know a lot of people who are here, still active on here, but that is due to a mixture of things. This place is still popular, and I'm sure people will be able to sell things again.
Though, honestly, the staff here mostly sucks and haven't listened to us since like... 2013? I think that's a big problem.
I will make piggygators popular again.