For what it's worth, I too upgraded to the Pixel 8 Pro, and similarly ran across another Nextapp app delisted, SystemPanel2: https://xdaforums.com/t/app-4-0-roo...-does-not-clean.3552690/page-12#post-89101122
Normally the dev is pretty communicative and engaged with the community but has been noticeably less so over the past several months. I'm really hoping everything is okay with them!
Over the past four years at least. Since the pandemic began, if not earlier. In fact there was a bunch of people worried ( I was one of them ) about Liebeck being a victim of the disease.
It's unfortunate for us when it comes to FX, but everyone has a life. Development has taken the backseat in his, and that's fine.