[Animats]

Yes, that looks like a problem:

...to distribute or communicate copies of the Original Work and Derivative Works to the public, with the proviso that copies of Original Work or Derivative Works that You distribute or communicate shall be licensed under this Transitive Grace Period Public Licence no later than 12 months after You distributed or communicated said copies

It looks like the effect is that the public versions must always lag a year behind the proprietary versions.

So, this isn't open source, although it is abandonware protection.

[mncharity]

> public versions [...] lag

That was the ghostscript licensing for many years. Recent versions available under a commercial license, and older versions as open source.

Nowadays would have to worry more about security and backporting fixes.

One challenge is it discourages contribution.