downgrading to an older firefox version with the same profile was never something that was supported by mozilla - recently (i think since firefox 67) they have also implemented this dialog to make users aware of this.

that sound right. I haven't had to downgrade for a while.

I manual restored my bookmarks and add-ons. Is there a options to download the configuration of firefox?

You can possibly disable auto-fill for login forms via the about:config page.

• signon.autofillForms = false
• signon.autofillForms.http = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

See also the checkbox here:

• Options/Preferences -> Privacy & Security: Logins and Passwords: "Saved Logins"

• https://support.mozilla.org/en-US/kb/automatically-fill-your-address-web-forms
• https://support.mozilla.org/en-US/kb/control-whether-firefox-automatically-fills-forms

Why would I disable autofill?

what does that have to do with Firefox configuration saving?

Mace2 said

I had a problem where cached information was being placed on login forms automatically...