RE: the shape of the menorah in 770 and around.
There can be a billion and one reasons why it was more convenient to buy a curved Menorah rather than straight.
To name a few: cheaper; was the only one left in the store; didn’t want to spend money on a menorah so they picked one up that they found lying around; there was another menorah that you didn’t notice which was straight and the curved one were to appease the people who had the minhag of having a curved one; The scatterbrained tzfatim (whom Iv’e explained are not your example of a Lubavitcher. they are a radicalized group of youth who go crazy all the time. never confuse a Tzfati with a regular Lubavitcher.) were not paying attention and they bought the wrong one etc.