No longer open-source?

[ErikSwan]

I could have sworn the draw.io source code used to be fully open-source, but I've come back recently to report a couple of bugs and I noticed that a lot of the source code in the GitHub repository is now minified, and the README now states (emphasis mine):

The minified code authored by us in this repo is licensed under an Apache v2 license, but the sources to build those files are not in this repo. This is not an open source project.

This is a big bummer, because it makes it pretty much impossible for me to go and fix annoying bugs I run into myself and then contribute those fixes back.

When did this change occur? Is there an announcement or discussion thread or blog post where this change to the license was announced? What was the reasoning behind the change?

I can't find anything in either the GitHub Discussions, or on the Draw.io Blog, so I'm left feeling like this was a stealth change.