Yeah, this one's common. You're probably using the wrong suction mode for your carpet. The cleaner head has a slider to adjust resistance.
Fix: Look at the front of the cleaner head. Find the suction control slider. For deep- to medium-pile carpets, you need to slide it all the way to the left. That's the setting meant to make it easier to push. If it's in the center (for low-pile) or right (for hard floors), it'll be a beast to move.
Also, check that the brush bar is turned ON (using the button on the left side of the handle). An inactive brush bar can sometimes increase drag.
If that didn't work: There's likely a massive hair wrap around the brush bar jamming it. Unplug the vacuum, lay it down, and remove the brush bar from the cleaner head to clear it. Also, make sure the bin isn't filled past the MAX line—overfilling kills suction and makes it harder to glide.
Heads up: The de-tangling vanes are supposed to clear hair as you go, but they can get overwhelmed. Regularly pulling the brush bar to clear wraps is key for high-pile carpets.