Mail attachment formatting errors when opening on iPhone iOS 18.4.1

An email recently sent from my outlook.com had a Word file attached. The email recipient notices numerous formatting errors in the attachment.

When I open the attachment on my Windows laptop, it’s error-free. When I open it on my iPhone (ios18.4.1) I see the errors. When I open it on Word on my iPhone, it’s error-free.

SOS?

[Re-Titled by Moderator]