I have always used the apple menu to access my bookmarks. I only ever opened my sidebar to rearrange them. (drag and drop) but since upgrading to safari 26, I could no longer use the sidebar to rearrange bookmarks. then I was pointed to "edit bookmarks" from the apple menu, where I CAN still drag and drop. and this is a sequoia problem. apparently on Tahoe, it's not all that difficult to set it up where drag and drop works in the sidebar.
so basically, to me, the safari sidebar is now obsolete. :)
For those of us on Sequoia, and unhappy with safari 26, there is another option. you might want to look at FitzltEng’s reply in this thread. You can lay Sequoia in place over the Sequoia with safari 26.0.1 to end up back on Sequoia with safari 18.6 without a system wipe and reinstall.
if you would like, you can send feedback to apple. if they don't hear from us, how will they know there is an issue?
Please see Feedback - Safari - Apple.