There's already rent control in the biggest areas. There's capital gains tax on rental property sold is almost 50% if held less than 20 years. Non-resident landlord tax is similarly high. French landlords still owe 30-45% on income, plus a 17% social charge.
It's not a surprise that if you tax something, the price usually goes up.
It's not a surprise that if you tax something, the price usually goes up.