Pages send a copy as Word changing formatting

Apologies if this is covered elsewhere but I can't find the answer and so I need some help.

I'm trying to send a Pages document as a Word file using the 'send a copy' function but every time I do it changes

the formatting of the document?

The font changes from Tahoma to what looks like Times Roman, font sizes and spacing changes, justification changes etc

If I send a copy as PDF everything is fine and just as it was made in Pages, but as a Word doc it all goes screwy.

This is the first time in months I have had to do this and it always used to work fine so I'm confused.

Any thoughts?