Just FYI I installed the apk from the github repo (not the google play version) via Obtainium a few days ago and it tried to make a connection to 2 cloudflare IPs during setup of my account. Without prior consent or any mention. So just be aware that there is still some form of telemetry or unwanted connections happening, even though they removed the telemetry flowing to Mozilla's own telemetry endpoint. K-9 had zero of this, it just spoke with your mail servers and that was it. So be careful and block outgoing app connections by default. I did not analyze the data being sent, just that there were those 2 unwanted connectiins happening.