That's why I said "IF", but the later seasons of Buffy were released in 1.78:1 format
In the UK and Australia, yes. But at the behest of Joss Whedon, the US release was 4x3.
And when you watch the 16x9 UK releases, you can see why. Empty space around characters huddled together, lighting equipment in the shot, wires coming out of props where they should not be, stagehands in frame holding "demon pieces" and people waiting for their cue to enter a scene.