I've noticed that dark reader on occasion phones home to darkreader.org, also with a increasing amount of sponsored links on their page. So what does everyone think, are they safe right now or should they not be trusted?
If you don't know how to read code, then you pretty much have to trust them, and all other open-source software out there. The good thing with FOSS is that there's probably someone who cares about it enough to read it and audit it, although there can also be a chance that no knowledgeable person cares about the code so no one ends up actually knowing what it's doing.
I don't know how to read code, so I pretty much have to trust all of the FOSS that I use. Although open-source is usually more trustworthy than proprietary counterparts (read: PRISM)
FOSS is only reliable if it is maintained and has an active community. With FOSS that hasn't had updates in years, as sometimes found on GitHub, Gitlab and others, you have to take it with a grain of salt.
We must not forget that being open source, it is also easy for malicious actors to discover security holes or inject some malware, which in a software that lacks supervision or is abandoned is not discovered.
Although it is true that FOSS is usually quite secure, it is not carved in stone and you always have to be careful, as with any other software. Security and privacy always depends on the dev or the company, it's irrelevant if it is FOSS or not. The APIs to track userdata and log its activity from Google, Amazon, Fakebook and others, are all FOSS.