It is very difficult to tell if a program is respecting user's privacy without the source code to verify what it's actually doing. When you can't see or change what it does then the developer is the one in control of the computing, and even a good intentioned dev will have to resist the temptation to gain at the user's expense.
Being open source doesn't prevent the software being made with features one may dislike. It does mean you can actually investigate what data is being collected and decide if it shouldn't be doing that.
When I have installed Windows I've clicked "no" many questions asking if I was X feature on, and I could only hope it was respecting my wishes. It was probably still collecting data it didn't even ask me if I could turn off.
It is very difficult to tell if a program is respecting user's privacy without the source code to verify what it's actually doing. When you can't see or change what it does then the developer is the one in control of the computing, and even a good intentioned dev will have to resist the temptation to gain at the user's expense.
VSCode is open source and yet Microsoft still pushes telemetry crap into it.
One advantage of FOSS is that you can fork it! VSCodium (presumably, I never really checked) takes all of the crapware out of VSCode.
Being open source doesn't prevent the software being made with features one may dislike. It does mean you can actually investigate what data is being collected and decide if it shouldn't be doing that.
When I have installed Windows I've clicked "no" many questions asking if I was X feature on, and I could only hope it was respecting my wishes. It was probably still collecting data it didn't even ask me if I could turn off.