Deleted his entire gallery around early 2021. Most of it plus more is available on his Patreon which I donate to and I have been thinking about posting some of his stuff from there but I'm slightly worried he'll find out.>乾杏子
He has a second Pixiv account where he posted more R-18 content but in early 2021 he deleted his gallery. Since the second account has a Pixiv fanbox I assume he's doing something similar to PersonaNonGrata. >Uzushio
I've already talked about him before. He's been drawing really good stuff since the early 2000s and maybe even the late 90s but due to some negative interactives he had with foreigners which I don't 100% know the details of he stopped publicly uploading his work around late 2015. He isn't too fond of non-Japanese people and only talks to and shows his work to people who he trusts. I've found a lot of his work archived on ExHentai but I'm pretty sure that his twitter account (which tweets are protected) has some really good new stuff.
And those artists are people who we know what happened to, there are many more artists out there who no longer draw scuba stuff or just don't draw anything anymore (for various reasons)
If you want to get good at drawfagging continue to keep drawing and drawing. Remember to challenge yourself but also remember that all drawings are just shapes put together.