Tonkatsu Sauce for Everyone! (*꒦ິ꒳꒦ີ)
The artist is a Chinese artist named Jeacn.
Yes, they exclusively posts to e621.net nowadays. I checked all available reverse image search tools and cannot find their artwork anywhere else. They did have a DeviantArt account a long time ago, but it hasn't been updated in 14 years.
hey im actually the one who has been uploaded jeacns art on e6 but only to archive them. he's stopped posting online since 2018 (from what i know) and the last thing posted was in a doujinshi ive been trying to get my hands on. not sure where he is now but i just wanted to make it clear that im the one who has been uploaded those recents pics and not the actually artist ^^