Did they do the bikechange in slow motion? There is no way a bikechange without a crash takes that much time. The GPS times were complete rubbish as proven by the GPS times that had Van Aert ahead and then suddenly had Ganna 12s ahead.
A bikechange, including slowing down, getting off, hopping on and get going... is roughly 10s . Then you can add some time to get up to top speed again and to get into your rhythm. But there is no way he lost more than 20s.
Just looked this again, from racespeed to racespeed, rollout+bikechange+acceleration is +-25s.