Some didn't want Hart replaced and they didn't want his replacement to surpass him so they booed and jeered him until he lost all confidence and then they looked right. Then they cheered him being replaced with a different goalkeeper they had previously slated. They ignore all evidence that Bravo to replace Hart was on paper an improvement (and they had similar seasons last year).
Luckily Ederson can have a similar season and be brushed off as a learning curve, adaptation period, no protection because he's young and he's replacing a keeper we want rid of.