For people who often manage flowers, it is very common that flowerpots are nested together and inseparable. Remember not to worry in this case, haste makes waste. You can try to put the nested flowerpot down and roll on a dirt road, preferably not a peaceful dirt road, so that the flowerpot can receive a slight vibration when rolling and will separate after several times.
Or tap another ceramic basin on the bottom of that ceramic basin and tap the crowded edge. Remember, attention will come out.
Or find a bucket, add water, put the flowerpot in, and use the buoyancy of water to open the flowerpot. Then, take the flowerpot inside and move it slowly to see if it can be opened, or find something to tap slowly and gently, which should be able to open it.