Can’t exit page without “Changes that you made may not be saved.” warning

Since the latest update I can’t navigate away from any Page Builder page without getting a prompt saying “Changes that you made may not be saved.”. This happens regardless of whether I’ve made any changes or not – I simply open the page in the back end and then try to leave that page without touching anything and the warning appears.

This is happening across multiple sites, all with the latest update to Page Builder. Sites with the previous version do not exhibit this behaviour.