What program can spontaneously change the id_rsa file?

Question

SSH

I create a key with the command

ssh-keygen -t rsa -b 4096 -C "[email protected]"

The key is written to the ~/.ssh/id_rsa file. I use it successfully throughout the day (for git push to github.com). And the next day I discover that pushing is not possible. Found out that the file ~/.ssh/id_rsa had changed (there was a long text, but in the end someone shortened it by half). The public key has also changed. And so constantly, I change the key, and not the next day again it is changed.
How could this happen?
This is happening already on three virtual machines that I create on c9.io.

Answer 1

c9.io support responded.
It turns out the problem is that the id_rsa file is constantly being overwritten.
https://community.c9.io/t/which-program-can-sponta...

cloud9 puts an autogenerated ssh key into ~/.ssh/id_rsa.
You can add that to github, or put your key into ~/.ssh/id_rsa_github, and add a config like
Host github.com
User git
Port 22
Hostname github.com
IdentityFile ~/.ssh/id_rsa_github
TCPKeepAlive yes
IdentitiesOnly yes
~/. ssh/config