I agree that it should be "affect". Affect doesn't look wrong to me:

  and technology choices made in Firefox can and do affect Thunderbird, just like they effect e.g. Zen Browser or Tor Browser.

English is a bit of a bastard language IIUC, and so we accept the way you've phrased it too, but in that case it should be "affect".

I hope this helps rather than making things more confusing! ;)