EDIT: It seems this made it to HN. Is this my cue to Soatokify this article?
The NightOwl application has existed since 2018 and is used to automatically switch between light/dark modes on the operating system. It is an alternative to the built in macOS automatic mode which only switches when the user steps away from the computer.
However, the application has been bought out by “TPE.FYI LLC” in late 2022 that forcibly joins your devices into a botnet for use of market research, without your knowledge (other than the TOS in small text on the download page) or express consent (this feature cannot be turned off, even when the app is quit). This is documented in their terms of service.
Something being open source doesn't automatically make it safe to use. Sure, it means it's easier for people to check for security issues, but how many people actually have the knowledge and the time to do it? And even then, take the log4j vulnerability from a while ago, it's been present in the code since 2013 and only reported in like 2021.
You still need to build package and install it yourself though or else you are trusting someone else.
Open Source software has been used as a vector for attacks before by bad actors getting access to the build system or source code.
You need to examine your devices packets and see what servers they're going to. You can do that through Wireshark on Windows, or use an external sniffer to examine them.
I'm not aware of any native apps for Mac that can do that, but maybe others will know.
If you're just interested in connections (and don't care about packet inspection) you can use Little Snitch (paid) or LuLu (FOSS).
Actually, all the Objective-See Foundation security tools are great and target specific classes of vulnerabilities, like LuLu for outgoing network connections, RansomWhere for detecting ransomwear by looking for encryption events, Oversight that monitors you cameras and microphones and a bunch of other really small, but really useful security utilities. Better than running a shady antivirus that's going to suck up loads of resources and rely on signatures.
Vigilance. Resource monitoring and network traffic monitoring. The occasional scan with anti malware tools to catch known bad actors.
I use malwarebytes when someone needs a scan, though they got naggy enough that I uninstalled it right after using it for my grandfather. Other monitoring IDK. LittleSnitch is popular on Mac but I have no personal experience with it.
This should be illegal by European law. Without further knowledge it seems like a prime example for the GDPR letter of death and a pretty solid case for data protection lawyers
But various forms of backstabbing are legal as long as you let your users know that the TOS have changed. I mean, who reads that stuff anyway. You can literally throw in there whatever you like and people will just click “I agree” regardless.
Light and dark mode can be set to turn on automatically at a given time or can be set via sunset/sunrise. Not sure where you got people need to step away from their devices to enable.