I had the same problem when learning Japanese. Whether teachers or friends, I didn't often speak it with other men, and definitely picked up some softer turns of phrase and pronunciations.

Once I became able to hear this in myself I started overcompensating somewhat, and had a few people comment that I sounded unusually brusque or was saying something almost cartoonishly masculine.

I don't think there was anything inherent in the language that changed my personality, but it definitely added another layer of concern and thought to how I interacted with people. A lot of it also had to do with just the more limited set of words available to me, though. Maybe I wanted to say something snarky or yell at a taxi driver or whatever, I might just not have known how.