The EU has a large problem with carbon leakage from electricity generation to oil and gas use.
For example, gas heating is exempt from the EU carbon trade, so people are encouraged to use that rather than electric heating. In countries like Germany, gas heating is popular largely for tax reasons.
Gas heating is a pre-existing issue in Germany. While there is handful on anecdotes of someone switching back to gas, the big trend is opposite. Majority of heating refurbishments are gas/oil -> heat pumps, and almost every new build is heat pumps.
carbon leakage is mostly industrial and data centers (why do so many europeans run code at us-east-1 ?)
If you study the heat pump adoption in various European countries, you will quickly notice that it's connected to the price ratio between electricity and gas.
The EU has a carbon tax on electricity but not gas. This pushes people towards gas heating. Germany has much higher taxes on electricity, although it does at least have a carbon tax on gas.
If a carbon tax on electricity makes people use gas heating, that's carbon leakage.
For example, gas heating is exempt from the EU carbon trade, so people are encouraged to use that rather than electric heating. In countries like Germany, gas heating is popular largely for tax reasons.