Roglic didn't have that bad of a day as he only lost 30 seconds to TomDum (the World TT champ and a grant tour winner himself, i.e. not a one-trick pony rider like, say, Tony Martin). He didn't have a great day, but he was not supposed to need to have a great day to win with a minute ona. guy who won the previous TT from him by just 8 seconds. It is that Pogacar's performance was out of this world phenomenal. And given that this is cycling and TdF, the suspicions are natural.
And I don't think you can peak at the end of a week 3 of a grand tour where you had no support in the mountains almost all week. Jumbo was not as dominant as Sky, but they did everything right and Pogacar beat them essentially alone. A Cindrella story, yes, but suspicious nonetheless. And no suffering indeed. Pogacar was upright at the end of the TT, when Roglich collapsed to the ground.
And here is Dumoulin in his own words talking about his power output at the time trial : “My values were World Championship-worthy values. That's great to see," he said. "That's why I was all the more surprised that Pogačar was 1:21 faster.”