Is this flowerpot insert made from asbestos?
Until you have it tested, you'll never know. Asbestos doesn't really pose a health risk unless it's frayed or crumbly and the particles are released into the air and you breath them in over a long period of time. If those inserts are outside and you're frequently watering the flowers, you should be fine.  If you decide to just get rid of them as a precautionary measure so you'll sleep better at night (I wore a facemask, gloves and a face shield while taking the last picture), just empty out the dirt and dispose of them properly without breaking them up,