iPhone 11 Pro video recording volume very low

Noticed this today. Video recordings in the camera app have very low volume. Tried soft reset, cleaning all mics, taking case off. Not on silent and all volumes turned to max. Volume fine when playing music through speaker or watching a YouTube video. Problem is with both front and back cameras.

Strangely, works perfectly fine when video recording in another app (eg WhatsApp) and voice recording app. Problem limited to new recordings through camera app.

Any help appreciated.