So you have to wait, until it goes back to 800, and if it doesn't?

And if you have to make a bridge from the ethereum network to the polygon network, they charge you a fee for the network transfer

But if you have the eth in the Polygon network, the Polygon network commissions are very cheap.

You can add a few cents for free to your metamask account with the faucet link above in the post and make your first transaction on the Polygon Defi network