OHIP offices have started asking for a valid PR card. You could sue because it isn’t technically a requirement. Many examples of others on the forum who have had to wait the 2-3 years until they could get an OHIP card.
Do you know if this is universally practiced by all Service Ontario offices? If it is only true for some locations, or even tellers, then I guess a PR can always go to another office and try their luck there.
BC, for example, does not mention that they would accept CoPR as proof of permanent residency, whereas Service Canada only mentions IMM-1000 and PR card (other forms of CoPR would only be accepted within one year of landing).
Service Ontario, however, explicitly mentioned that either IMM 5292, IMM 5688, IMM 1000 or PR card is accepted as proof of permanent residency for the purpose of applying for OHIP. You would think that they would mention this on the website if they were to make PR card a requirement (and this would also mean that hundreds of thousands of new PRs would not be able to get health care until at least 3 or 4 months after their landing).