Yeah, this one's common. Weak suction is almost always a full bin, a clogged filter, or a hidden blockage.
First, empty the bin. Don't wait—empty it as soon as the dirt reaches the top mark. Overfilling hurts performance. Hold it over a trash can, pull the bin release catch up, and let the base open.
Next, check the easy blockages. Pull the wand off and look in the connection point on the main body. Check both ends of the wand itself. Flip your cleaner head over and clear any hair or string wrapped around the brush bar.
IF THAT DIDN'T WORK: Your filters are probably packed. You need to wash both. The Pre-filter lifts out of the top of the cyclone. The Post-filter twists off anti-clockwise from the back. Wash each under cold running water until it runs clear, then shake out excess water. Here's the critical part: let them dry for at least 24 hours in a warm place. Do not use the vacuum until they are 100% dry.