Hi,
You can try this: first, reset Microsoft Edge settings by going to Settings > Reset settings > Restore settings to their default values, this helps if a hidden configuration is causing the tabs to close. Second, disable "Startup Boost" and "Continue running background extensions" under System and performance in Edge settings, as these features sometimes cause instability. Third, create a new Edge user profile to check if the issue is linked to a corrupted browser profile. Lastly, update or reinstall Edge from the official Microsoft website to repair any damaged files. After trying these, test Edge without any sync or sign-in first to see if it stays stable.
Kind regards,