Your Plan F is a Medigap supplemental policy, no longer available to new enrollees since 2020. The closest Medigap plan available for enrollment today is Plan G, which does not cover the Medicare Part B deductible. Plans F and G also have the most expensive monthly premiums for Medigap supplemental policies.
I had it since before I retired and continued it on into retirement, and it’s always paid everything of the leftover 20%.
I’ve paid no copays for office visits nor have I ever been billed anything for any of the times I’ve been in the hospital since retiring (4 times). It is very expensive but plannable and manageable and I don’t have to worry about what ifs....