Why are documents now displaying tiny cells and none of my cell text is visible.

Opened this application today to find this. 

The view is damaged or corrupted so that there are hundreds or thousands of cells visible in the viewport at 100% view scale.

Zooming in does nothing to improve this.

Zooming out to 10% then appears to show some of the text very small in the top left of the viewport, until zoomed in again at which point the text disappears once more. 

What is visible is very clear in the screenshots attached to this post. 

We have attempted an online repair of microsoft 365. this has done nothing.

All existing documents persist in showing this. All new documents persist in showing this.

We do not know what windows updates have been done. Nothing has been done by us.

We do not know if any changes to drivers has occurred. Nothing has been done by us.

We are looking for advice or knowledge from any user/s who have seen this specific issue before.