PlayStation 2 emulation on Android was in a pretty poor place for years, with there being very few options for people who wanted to play some of their favorite older titles. The only real option was a closed-source app that was for-profit, with allegations of stolen code shrouding any semblance of credibility that it had. That's why AetherSX2 was a big deal when it was first announced, as it was free, open source, and had the blessings of the PCSX2 developers. However, now it seems that the developer of AetherSX2 has called it quits, citing "neverending impersonating, complaints, demands, and now death threats."
As Tahlreth, the developer, explains, the app will continue to function for the foreseeable future. There won't be any new updates, though, and he has warned against scammers popping up in his place pretending to be him. The developer has been contacted across multiple channels by people constantly requesting features and fixes and making complaints. AetherSX2 was always a free app without any warranty developed by one person, and Tahlreth said that he felt that "this is just a handful of haters blowing something well and truely [sic] out of proportion."
For what it's worth, AetherSX2 is currently in a great place as it stands, and you'll be able to play games on pretty much any modern flagship released in the past couple of years. It even runs on MediaTek devices now when it didn't previously. As for any future problems that may arise, wellll there won't be any fixes for those by the looks of things, but the emulator has been in a great place for a long time, anyway. You can still download it on the Google Play Store for the foreseeable future, and it's a more or less perfect emulator aside from a few smaller issues.
For now, it seems that the AetherSX2 project is well and truly done. As Tahlreth puts it, "It doesn't make sense to continue working on a hobby which isn't fun anymore." Older APK files are still available to download from the official site. The legacy of AetherSX2 won't be forgotten, as it allowed many people (myself included) to relive childhood memories from the comfort of their smartphones.
You can download the app and give it a try from the Google Play Store, linked below.
Source: AetherSX2