English speaking skills

How good should my English be for tech interviews. As an immigrant I feel a little insecure about the way I speak. I've been speaking English since childhood but since I come from a non-western country, I have trouble communicating at times.

I've seen Glassdoor reviews of employees complaining about accents and communication. I've also seen reviews where candidates have claimed discrimination based on the way they speak.

Is this a serious issue?