Did we ever disable that using namespace juce by default? If we haven’t done so, we should, and should probably deprecate it more aggressively too.
If you’re having that kind of problem in your code, the thing to do is to turn off juce’s using namespace juce and instead add your own using, which you can put AFTER all your headers, or inside your own namespace, so it can’t interact with any headers from the system or other libraries.