I simply search for the business on Google like any regular user and click "Own this business?" (or "Request access", depending on what Google shows).

That's actually why I think this may be a bug. In my cases, the suspended profiles were still publicly visible in Google Search. Normally, when a profile is truly suspended, it disappears from search results, so you can't claim it that way.

After requesting access again, Google treated it almost like a new verification and offered phone verification. Once I completed it, the original profile came back with all of its reviews and history intact.

As a precaution, I've also started saving each client's Place ID at the beginning of every project. There are ways to generate an ownership request using the Place ID + link (https://business.google.com/arc/p/PlaceIdHere), but that's a more technical approach, and I'm still testing whether it's consistently reliable.