One of the patches in bug 1698763 is similar to the patch in this bug. It should fix this issue, although there's still more work to be done to get toolbarbuttons looking more like Big Sur-styled buttons.
Bug 1699221 Comment 2 Edit History
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One of the patches in bug 1698763 is similar to the patch in this bug. It should fix this issue, although there's still more work to be done to get toolbar buttons looking more like Big Sur-styled buttons. EDIT: To be clear, I think we can close this bug after bug 1698763 lands. Styling toolbar buttons like Big Sur buttons is a separate issue.