Autofill fills data only once on a certain page, after refreshing the page, it just didn't do anything, after another refresh, this notification is displayed:

The only workaround is to remove page cookies and refresh the page again, so I assume some cookies are interfering, but I'm not sure why or what is happening. Worked flawlessly since yesterday.
Related to page: https://www.impuls.cz/halo-tady-impulsovi#impulsovi-formular and FF extension (FF 109.0).