nitter.net is an official Nitter instance (and most overloaded) known to be rate limited. But report to devs to check if there is other case or bug.[0]
Meanwhile try another Nitter instance.[1,2]
[0] https://github.com/zedeus/nitter/issues
[1] https://github.com/zedeus/nitter/wiki/Instances
[2] https://twiiit.com/ (redirecting proxy for Nitter instances)