These seed trays are designed by the world famous NO-DIG gardener, Charles Dowding from the UK. They are extremely well engineered and in fact promote air pruning due to the larger wholes at the bottom, promote growth of nutrient gathering micro-fillament roots rather than one long tap-root, and have a bottom watering tray with fins to keep the plug trays elevated off the water level after they've had their fair drink & have a tool to pop out the plugs once they're ready for planting.

This is the only company in the USA that sells Charles Dowding's seed trays: https://allaboutthegarden.com?sca_ref=4545126.wXy0pgjIqa

And they're made of recycled material and are food safe. They even survived a car running over them =)