It looks like this is a Chrome only service, so when my chromium installation gets janked and I have to switch to Firefox, then my bookmarks are lost again.
It also looks like this is a Google service which means if Google sunsets this service, which is not unlikely considering their history, then my bookmarks are lost.
It looks like it's also tied to my Gmail account which means if I don't have a Google account, have multiple Google accounts that I want to keep separated or lose access to my account Google account, my bookmarks are lost.
All the above scenarios, with some degree of generality, have happened to me before in one form or another.
