packages held back

[diederik]

I ended up runnig apt install mobian-base mobian-phone-base mobian-phosh-base mobian-phosh-phone.
As far as I remeber it's safe than full-upgrade when running testting and sid.

FYI: No, that doesn't matter.

If you have enabled both Testing and Sid and not configured 'other' things, then you're actually running Sid.

What often happens when both get enabled, is that Testing is made the default. Run "apt-config dump | grep Default" to see if that's the case.
When Testing is the default, then you do things 'in' Testing, unless you explicitly specify otherwise (via f.e. "-t sid").

APT selects the package/version whose priority is the highest and if the priority is the same, then it takes the highest version.
When you set Testing as Default-Release, then Testing gets a priority of 990 vs the standard of 500 (for Sid).
See "apt-cache policy" for the general settings and "apt-cache policy <pkg>" for a specific package.