One of the main benefits of open source software is that you can build it yourself or verify that a built blob is what it claims to be. If you’re using someone else’s instance then you don’t know that they haven’t made a change to it that could be doing something malevolent under the covers.
Because it’s open source software and things such as mod logs are public to all.
And it’s not about privacy, it’s about manipulation.
One of the main benefits of open source software is that you can build it yourself or verify that a built blob is what it claims to be. If you’re using someone else’s instance then you don’t know that they haven’t made a change to it that could be doing something malevolent under the covers.
Luckily I’m self hosting, but you’re right there is a risk.