he didn't sell it, he wanted to stop development and gave it to someone else, who turned out not to be trustworthy, so he made uBlock Origin.
uBlock Origin Lite/Minus are a response to googles manifest v3, which will be mandated soon, taking away some of the APIs needed for uBlock Origin to stay as effective as it currently is. So this is basically a neutered version of uBlock Origin, because the original version will cease to be able to exist in its current form on chromium (but not firefox)
Pretty sure he just passed the torch off to someone else (without selling it) because he was tired of it, then continued development shortly aftwards as "ublock origin". uBlock itself (not origin) got sold off the Adblocker Plus and allows some ads.