In my experience, the more you are around someone, the more you begin to behave like them. As you get used to their behaviors, that behavior normalizes for you, and you eventually begin doing them yourself.

I don't see how this can differ in terms of personality traits or the "vibe" that other people get off of you. If you're around a toxic person, you begin subconsciously adopting their toxic traits, and even if you don't realize it, or even use the traits you've adopted, other people can tell. Your body language changes, your thought process and speech patterns change, and it displays the same as a toxic person even when you are not.

A common example of "osmosis" as it were, would be a British family spending a long time in the USA until, eventually, they can precisely adopt the American accent while they are out - but the moment they get home, the people they have associated with the longest (as well as their traits) begin to show in them.

It's not suggesting that environment alone is the factor, but also the prolonged exposure to a specific behavior.

Really the best way to get rid of the cold vibe is to get back to your true self for a while, and avoid the toxic person entirely. You'll actually even FEEL the difference.