Does verbal offer mean anything these days?

I’m currently under CPT, looking for internship or any kind of employment. The day after my final interview with this company, HR called me with a verbal offer. They said I would receive the official offer letter within a week—which I did, after a few days.

I went through all the onboarding process, and the onboarding coordinator confirmed that everything was finished on their end.

But just the next week, I got an unexpected email from HR, saying they had to put things on hold due to “conflicting information”, and that they’d follow up on Monday.

I got this internship through a 3rd party staffing company. What should I do now? I don’t have time to search for another internship as the summer is almost over. I was supposed to start the position in early July.

Even after completing onboarding, can an offer still be withdrawn???

I’m genuinely looking for thoughts, suggestions, or shared experiences from anyone who’s gone through something similar.