There's a difference between a character overtly acknowledging and addressing the camera and a character just staring into space in a direction that the camera happens to be in. For instance, in
the closing shot of "Journey to Babel," McCoy is facing the camera, but his eyeline is just off to the side of the camera instead of directly into it. If you saw someone looking toward you that way, you'd conclude they were looking at something over your shoulder rather than meeting your gaze directly. He's not literally addressing the audience; in-story, he's talking to the other people in sickbay. Metatextually, it's meant to resemble him addressing the audience, but it doesn't make it explicit enough to break the reality of the story.
This is a pretty common thing in shots just before ad breaks, to have the camera pointing head-on at a character to focus on their reaction, but that doesn't mean the character is actually looking
at the camera. Just doing a head-on close-up is not enough to qualify as breaking the fourth wall. That requires the characters to look directly
at the camera and speak to the audience, as opposed to looking in its rough direction while speaking to themselves or others in the scene. Or it requires them to say or do something that acknowledges that they're fictional characters. That sort of thing does happen, but usually only in comedies. I remember Gilligan speaking directly to the camera sometimes or the Skipper throwing an exasperated look at the audience. The
Green Acres cast were constantly aware of the onscreen credits or the background music, to the endless confusion of Oliver, the one character who lacked their Deadpool-like metatextual awareness. And then there's something like
The Monkees, where the characters were constantly aware they were on a TV show and constantly tearing down the boundaries of the fiction, even to the point of storming off the set and heading to the writers' room to complain about the script (with the writers turning out to be a room full of chimpanzees with typewriters). Which goes back to the style of radio comedians like Jack Benny and Burns & Allen, whose shows were part-sitcom, part-dramatizations (comedizations?) of the making of the shows themselves, so that they constantly straddled the gaping hole where the fourth wall would be.