I’ve referred to myself as a German taxpayer the same way I call myself a permanent resident of Germany, and feel this entitles me to write my local member of the Bundestag - who apparently agrees, responding with a far more direct email addressing the topic than I’ve ever gotten from my US senators or congressman.

I am a bit bothered by things that say “BürgerInnen” have the right to something all legal residents have (like the Covid-19 vaccine), for fear that some of the less foreigner-friendly types are tacking on a “Staats-“ prefix in their heads, but that’s on me.

I honestly just read that as "people who pay taxes in Germany"

Yes, that's the correct use of the phrase and how exactly how it's being used 100% of the time.

It's the tax that is German, not necessarily the payer. Also when it comes to foreign citizens paying taxes in Germany it is a bit more nuanced. In general German tax law goes to great lengths to avoid double taxation, so no matter who you pay your taxes to you are treated fairly.