My first two examples are a bit of a cheat, because they are already there - just on a way to high tech level from my point of view!
Currently that tech is in Propulsion, 4 whole groups away from the starter techs.
History: The thing is, we had electrical Motors and batteries done by 1800 to lastet 1900.
What killed it: Fossil Fuels. Simply put, refining and putting Gasoline into engines prooved to be way more convenient. As a result, battery technology more or less stalled. The reason Electrical Motors are not as good on earth, is because they were 100-200 years behind Fossil Fuel Burners.
And especially during colonisation of moons, using Electrical Moters makes a whole lot more sense then Fossil fuel burners. Planets that have open air farming can propably get by using Biofuel Plants, but everyone else really has no reason to even restart with that.
Gameplay effect: Electrical Motors become avalible at way lower tech - propably with fuel burners. However, the early ones may not be very efficient. Both "Fuel" capacity and consumption may be very unfavorable. Additional techs would improove that, until we get to current day tech around Advanced Chemistry or Propulsion.
Gas Powered Small Arms
Currently that tech is in Advanced Engineering, 3 Groups from starter Techs and 2 from Automatic Rifles. Again, way to deep..
History: Originally I thought the idea of using Air Rifles as miltiary gear was not sensible. But turns out, it is very sensible.
What killed it: The Air Reservoirs. With the technology back then they were very hard to manufacture, very fragile and refilling them was a (literal) chore.
With pumping and manufacturing tech somewhat more this century it should not be an issue. We put gasses into tanks all the time!
Gameplay effect: It would stay a low ammo-consumption gun. It would just come before Automatic Rifles, rather then after.