It is just an old tip issued at gov1 stage but not executed because opengov. I think that's the all info. It just a reward of contribution for substrate code.
You can get a tip for substrate PR.
You can find more information about it on the given websites.
These websites will tell you about the reward for contributing to substrate code.
There is an old tip that was not executed because of opengov.
The tip is a reward for contribution to substrate code.