if you listed an item above 20fg fee is collected before the sale. Up to 20fg fee is charged only after sale
Small distinction here. Up to 19.99 fg it’s collected only if the item sells. At 20 fg exactly, you will be charged the fee upfront… however, it will not count against your 25 item listing limit (you can have infinite items 20 fg+).
One more niche thing to add…
If you list an item for 20 fg or more, you get charged the fee upfront. If you then reduce the price below 20 fg through an edit, you will incur the fee after the item sells as well, double-fee!

Gl!