Years ago I had a variety of heaters fail and invested in going all Ebo Jager. That company has now been bought by Eheim (or whomever owns them) hence the name change. I'm not sure if the actual heater changed or not. In pictures it looks the same, but that doesn't always mean much.
IMO all heaters eventually fail in some fashion. Hopefully they fail off and it'll become apparent over a period of time that the tank has gone cold. The ones that fail on are a disaster IME.
Some of my Ebo started to show condensation inside the glass tube around the heater element over time. I'm not sure exactly how they'll fail, if at all, but suspect it's not good. I've been gradually throwing out the worst ones. Luckily I've insulated my fishroom well enough that I don't need a heater in every tank at this time.