Yes, sorry, my phrasing is somewhat confusing. In terms of energy they are faster, since more speed is required for higher orbits. They appear to be slower in a relative sense when observed from Earth — the Space Station or a Starlink sat will appear to be moving significantly faster than a satellite in medium or high-Earth orbit.

It also depends on the geometry of the orbit — an object in a circular orbit will move at a constant speed, while an object in an elliptical orbit will move faster or slower depending on which point of the ellipse it is.

I understood the parent comment to be focused on an Earth-centred perspective, since they were talking about Kessler syndrome and Earth-orbiting debris. I was trying to address that point from an Earth-centred perspective too, but I appreciate how that can be confusing.