How obese was he? It appears he lost a lot of weight since his early days.
I think people with a long history of obesity do not fully recover from the toll it has taken on their heart-lung system until (and if there is) a long period after great weight loss.
Meatloaf’s stage performances were like a giant physical work out, for an average weight person, which he was not, and the whole time while he had asthma as well. I do believe the late in life weight loss did not ever fully compensate for the prior history, in his case, and that history made him more vulnerable with a Covid19 infection - my guess.