Leave site prompt occurring after changes saved

[halibutblue]

After updating to WP 5.6.1, my site started prompting me about leaving pages without saving, even though any changes I had made had been saved.

What's happening: When I open, edit and save a page then try to leave the page I am prompted by a pop up that says changes have not been saved. This pop up also occurs when I only enter a page, do nothing, then try to leave.

Expectation: to be able to open, edit and save changes to a page, or any section of the site and move out of it to another section without being prompted.

Actions I took so far:

• I turned off all plugins for a conflict test & the issue persists.
• checked/upgraded PHP to 7.3.27
• I checked the error log
• Made sure the theme was current and notified the developer in case something can be done on their end.
• Looked in forums for the issue. Noticed it had previously been occurring in woocommerce. Our site doesn't use woocommerce. Also noticed people saying classic editor might be a problem. I disabled the classic editor plugin & it had no effect (this was also covered in the plugin conflict test above).
• I downgraded the WP version using a plugin. Taking the WP version back to 5.6 removed the issue. When allowed to update back to 5.6.1, the issue occurs again.

[hellofromTonya]

Hello @halibutblue,

Welcome to WordPress Core Trac! Thank you for reporting this.

We are tracking this issue in Ticket #52440. To keep focus in one area, I'm closing this ticket in favor of that ticket.

If you have any other information to add later, please use that ticket. Thanks again!