Render as video not available in the Export tab.

Have you tried resetting photoshop preferences settings?

If a Document has a single layer and no timeline  menu File>Export>Render Video is grayed out.  If a Document has as Frame Anination  Time line the render Video item will not be grayed out but it seems to take forever and a day before the render video dialog opens. If  the document has a Video Anination and you click on render video menu item the Render video dialog open right away.  If the documeny has layers but no time line the render video item will not be grayed out but in the Render Video Dialog you can not rendet a video, All that is posible is saving a sequence of Images files. On Windows 10. Howevet all PS 2021 versions 22.x have major issues.