@Marc Korbuly The only way to stop the sidebar from opening on every board load is to keep the board outside a Space.
Some context: when the Simplified UI/Spaces dashboard launched in August 2024, the sidebar opened on every load, likely as a nudge to get people familiar with the feature. Around November 2024, Miro began persisting the user’s choice, so closing it once kept it closed. The 2026 update brought back the always-open behavior without that preference, so it looks like we’re in another nudge phase.
It takes up a significant portion of the board depending on your screen size/resolution, and every other tool I use remembers when I dismiss a panel like this. Otherwise, what’s the point of dismissing it?
Upvote a feature request
I suggest that you upvote this wish list idea post:
https://community.miro.com/ideas/stop-opening-spaces-sidebar-when-opening-a-board-18863