In some countries, you can buy or rent a house in bitcoins. But what are the tax and administrative implications?

In France, you can, in theory, buy with BTC, but you have to pay taxes and notary fees in euros.

Since you also have to pay capital gains tax and (unless I'm mistaken) prove the origin of the bitcoins. Justifying the origin of funds when you won cryptos with games or airdrops and then sold them to buy btc 15 years ago is almost certainly impossible.
In the end, it doesn't seem so attractive to buy in btc in France because of the administrative and tax complications, in addition to the 30% capital gains tax (unless I'm mistaken).

How is it in your country ?