Is Stylish safe to use again?

https://robertheaton.com/2018/07/02/stylish-browser-extension-steals-your-internet-history/ is the original technical write-up that covered the Stylish ordeal. There was a more recent one posted in August by the same author that covers the updated version of Stylish: https://robertheaton.com/2018/08/16/stylish-is-back-and-you-still-shouldnt-use-it/.

The latest write-up notes that Stylish added an opt-in screen when you install the extension.

Personally, I think this snippet describes the author's stance on the update best:

Will SimilarWeb (the adtech company that owns Stylish) try to sneak in more underhanded tracking in the future? I don’t see why not. Can we trust them? In my opinion, no. [...]

It is also worth mentioning that the author recommends using an open-source variant called "Stylus".

You can block Stylish API in your hosts file and don't worry about it anymore.

0.0.0.0 api.userstyles.org