One of the extensions had 45213 installs, which is what the headline stated. But no matter how you count it, the rest of the extensions was far off 45k.

I read it as any extension with more than 45k installs.

If it's 45k total, that's a very small percentage of all installs.

Right, but the one with 45k installs wasn't malicious - sending os version telemetry isn't PII stealing