It's pretty late in its life, could be that anyone who would be a potential sale got one at this point? I remember that being, at the time, the reason for the sharp decline in Ocarina of Time sales in Japan, they effectively sold one to everyone who has an N64 so they "maxed out".
According this chart from Ars Technica the switch and ps5 were still growing during the same period so then the question would be why the number of Xbox potential buyers is so much smaller than the others.