If you're using the Canary version of Chrome, you might have noticed the reading list icon hanging out on the right side of the bookmarks bar, just under your profile pic and the main settings button. This is a new feature as of Chrome 89, hidden by default in the standard release but available via a flag, and enabled by default in Chrome 91 Canary. What's also present in that build, and which wasn't before, is the ability to hide it with a quick right-click.
If you're on Canary and you have your bookmarks bar visible, right-click an empty space in the bar. Near the bottom of the right-click menu are a series of options, which now include "Show reading list." Click this entry to remove the check mark and hide the Reading list button. To make it appear again, just do the same thing in reverse.
This is a nice option for those on smaller laptop or tablet screens, where horizontal space is at a premium. Though the reading list itself is available via flags in the beta and full release of older versions, this right-click option to quickly hide it is not.
There's never any guaranteeing what Google will or will not bring forward in Chrome, but this seems like a simple and natural enough extension of existing functionality that it will probably be retained in the transition. This is the kind of small tweak that can even jump ahead of version releases, so you might see it in Chrome before 91 makes it to the general release branch in a few months.