I noticed that when reading a paginated book in Zotero 7, the section of the toolbar with annotation tools slides some pixels to the sides at the moment of changing page (not on *every* page turn but it is easy to reproduce after a few attempts).

EDIT: originally I thought it was an epub exclusive issue but in fact it also happens with pdfs. I believe it has to do with the page number indicator changing width because of non-monospaced fonts and of changing number of digits.

macOS Sonoma with 7.0.0-beta.62+b15fb36f1.