I think there was also fatigue that plagued TTT&UA
I remember her canceling Graham Norton (where she was apparently going to do WHYB) but she got sick. Then she had 10days of promo in the UK but Dolly was sick then she died which caused a few cancelation. Remember when she got hospitalized around the MET Gala

Also during the end of LOUD tour(whicj was TTT start)
UA she got sick when she was supposed to perform+ interview at Le Grand Journal (but she did that french show later on) and she got sick when DWT was going to start.