I think for a while leading up to the recent session stealing hack, there has been a massive amount of positivity from Lemmy users around all kinds of new Lemmy apps, frontends, and tools that have been popping up lately.
Positivity is great, but please be aware that basically all of these things work by asking for complete access to your account. When you enter your Lemmy password into any third party tool, they are not just getting access to your session (which is what was stolen from some users during the recent hack), they also get the ability to generate more sessions in the future without your knowledge. This means that even if an admin resets all sessions and kicks all users out, anybody with your password can of course still take over your account!
This isn’t to say that any current Lemmy app developers are for sure out to get you, but at this point, it’s quite clear that there are malicious folks out there. Creating a Lemmy app seems like a completely easy vector to attack users right now, considering how trusting everybody has been. So please be careful about what code you run on your devices, and who you trust with your credentials!
But in this case, if an app is open source, there is a higher chance of discovering that it sends your credentials somewhere else than in closed source app
That assumes people are looking at that and know what they’re doing and aren’t malicious actors. None of this is guaranteed. Famous examples of major OSS security vulnerabilities have already shown this.