https://support.mozilla.org/en-US/questions/1376015
Affection firefox version 95+
(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.
More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.
(2) In the search box in the page, type or paste security.tls.enable_0rtt_data and pause while the list is filtered
(3) Double-click the preference to switch the value from true to false