Landscape mode in Mail - IOS26

To read an email with smallish print, prior to upgrading to 26, I rotate my phone and have full screen of the mail in landscape mode. On 26, instead of full screen I get split screen with a folder list on the left and cannot read the mail. Annoyingly, if when in landscape mode I tap the button to eg forward the mail, I get a full screen display of the reply + forwarding options.

This did not happen on IOS18!!!!!!

Can anyone advise if there’s a setting I need to change to accommodate this ?