Run these in CMD
Chrome Asking Default Disable
reg add "HKLM\Software\Policies\Google\Chrome" /v DefaultBrowserSettingEnabled /t REG_DWORD /d 0 /f
Edge Asking Default Disable
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Edge" /v DefaultBrowserSettingEnabled /t REG_DWORD /d 0 /f
Brave Asking Default Disable
reg add "HKLM\Software\Policies\BraveSoftware\Brave" /v DefaultBrowserSettingEnabled /t REG_DWORD /d 0 /f