[14:45] <dbungert> flaf: just looking at this now.  I ran a zero-touch autoinstall and my /etc/default/grub file looks like what I would expect.  Any thoughts on how to reproduce the problem?
[14:50] <flaf> Hi dbungert. FYI, in my case (with an auto install of Ubuntu 20.04), I have add this in my user-data file:
[14:50] <flaf> grub:
[14:50] <flaf>   replace_linux_default: false
[14:50] <flaf>  
[14:56] <flaf> dbungert: With these 2 lines in user-data, GRUB_CMDLINE_LINUX_DEFAULT parameter in /etc/default/grub is as expected (ie its default value from fresh install). Without these 2 lines in user-data, I had the same boot options as during my network installation (defined in GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub). So, in my case, these 2 lines were required.
[15:07] <dbungert> flaf: you mention using the 20.04 iso, do you know which version specifically?
[15:08] <flaf> dbungert: from https://releases.ubuntu.com/20.04/, ubuntu-20.04.3-live-server-amd64.iso sha256sum 8e3086f3cea0fb3fefb29937ab5ed9d19e767079633960ccb50e76153effc98
[15:09] <dbungert> flaf: ok, we're testing the same version.  Do you mind a bug write-up with details on how you're doing the install?  I had a pristine grub defaults file without having to set replace_linux_default false and I'm not sure what to test differently.
[15:11] <flaf> dbungert: I can file a bug report indeed, but not now (currently a little busy). But in a few hours, is it ok for you?
[15:11] <dbungert> flaf: absolutely, no rush
[15:11] <flaf> ok :)