Permissions for gateway created files under Linux (0644 changed to 0600)

I’m running an Ignition under Debian 10. From the beginning, all files created by the gateway, like wrapper.log or files written with system.file.writeFile, had a permission of 0644. That was expected with a umask of 0022.
A few weeks ago, the permissions of new files changed to 0600. I’m not sure if i updated to 8.1 on that day. Current version is 8.1.1.
Is there a Linux guru around who has an idea what happens here?

Haven’t seen that, sorry. Might be defaults for systemd service isolation that changed in Debian. (All of my Linux Ignition Servers are Ubuntu.)