At least and the least both use the same “least”. The context of their use mag be different, but if we’re sticking to strict grammar as written down by the booke, they’re both superlatives of “little”. The usage of less and least changed a bit when English dropped a bunch of grammatical cases over the years (“less of words” became “less words” because of this) but the word hasn’t changed much other than that the spelling got reformed a few hundred years ago to match pronunciation more closely.

I swear to god autocorrect is trying its bery hardest to turn grammar into grammer and I have no idea why. I’ve explicitly told it not to suggest grammer again but it keeps trying to incorrectly correct me. I blame AI.