It is not weird in that countries enforce what they see as antiterrorism laws outside their borders (US is a prime example). The problem here is that China is targeting essentially anyone with a strong critical voice.

Isn’t that pretty standard?

For example, Julian Assange, Kim Dotcom, and Richard O'Dwyer were all prosecuted for crimes committed outside the US.

Kim Dotcom and Richard O'Dwyer were pretty ridiculous, but Julian Assange was trafficking in what he knew were stolen U.S. government secrets. I think there's a good first amendment defence for Assange, based on the public good and his role in whistleblowing, but I can understand why the UK would extradite someone allegedly knowingly handling stolen state secrets of an ally.