How to prevent Firefox refreshing webpage when switching between apps

Hi, I have a Xiaomi Rednote 10 pro mobile phone. I have been a longstanding user of Firefox on numerous devices. However I am having real difficulties on my phone when switching away from the app and returning (for example to check a code for MFA). I have checked battery settings (unrestricted), background autostart (enabled). I've tried locking the app in the recent processes list, in developer settings "don't keep activities" is off and background processes is set to standard limit. Even with only 1 other app in memory every time I activate another app and return the page reloads and I lose what I was doing. I've tried uninstalling and reinstalling and have the most recent update. Other browsers on my phone such as Chrome do not exhibit this behaviour - when I switch apps and back again the page in the browser is retained. Is this a known fault with this type of phone? Am I doing something obviously wrong? Any help you can provide would be greatly appreciated.