A group from West China Hospital, Sichuan University, Chengdu, China, etc. has reported O-glycosylation of SARS-CoV-2 Spike proteins.
https://www.frontiersin.org/articles/10.3389/fchem.2021.689521/full
Authors have analyzed O-glycosylation of SARS-CoV-2 Spike protein expressed in insect cells and human cells. The numbers of glycosylation sites were different between insect and human ells (23 in insect cells, 30 in human cells), and also most of O-glycans expressed in human cells were sialylated. It is so clear that glycosylation of SARS-CoV-2 Spike changes with host cell types.