I had one of those electric immersion heaters years ago, they hail from the same days as electric bar heater. I wouldn’t ever get another. Mine developed a very tiny crack in it, you can imagine the rest. It involved an electric shock, an exploding cup, and a bad scalding.
I’m hoping you don’t have any similar problems, they heat up extremely fast if not immersed and will burn. As far as I know, they’re Chinese made and it would be well worth checking it meets EU standards.
Sticking with my tiny BRS 3000t Ti stove and gas canister, or Alpkit Jetboil clone for safe water heating.