Umask change in 26.04 when running binaries via "sudo -u"

[rubi1200]

Very interesting.

Thanks for sharing with the community.

The first thought that crossed my mind when reading your post was whether this might have something to do with the introduction of sudo-rs on Ubuntu.

Sudo-rs is now default for Questing Quokka

Hello, this is a quick update following the announcement of adopting sudo-rs as default in Ubuntu. Throughout this article, I will use sudo.ws to refer to the OG sudo and sudo-rs to refer to the reimagining and rust implementation by the Trifecta Tech Foundation . I will use sudo to refer to the general concept of sudo. sudo-rs 0.2.8 is now the default sudo in Ubuntu daily images . Upstream sudo-rs team did a fantastic job to implement all the necessary features in time for 25.10 Feature…

From that post, it links to this:

sudo differences

I am certainly no expert but this point might be relevant:

Sudo-rs always uses PAM for authentication, so your system must be set up for PAM. Sudo-rs will use the sudo and sudo-i service configuration. This also means that resource limits, umasks, etc have to be configured via PAM and not through the sudoers file.

My emphasis added.