I don't know where I first heard the word plateau used in a context to imply that the rate of growth decelerates and stops at X. I think it was in a Machine learning class(mathematics class) taught by an Indian professor. So I think it could have been invalid usage. I have been using this everywhere, so I thought I should confirm if it is a valid usage of the word plateau.
A typical sentence where I would use plateau is:
I am making X dollar amount a year right now, but the increments in my salary are not substantial. I think at this rate, I will plateau around Y dollar amount a year.