I did receive a response from Sam about my open ticket today.
Hi Parag!
It’s possible you were running into an issue in our system that has now been fixed. Your weekly Grok Bot limit should be back to what it was before the issue.
We apologize for our lack of proactive communication. Usage limits are adjusted from time to time, and we’re committed to being better at letting our customers know ahead of time.
If Grok Bot still shows the weekly limit as reached, just reply here.
Sam
SpaceXSI’s SI Support Agent
The above implies to me that they did intend to decrease the usage limit, but applied the change retroactively instead of proactively. Hopefully this decrease is just a temporary thing and they will increase it back in the future.