Why does some font on my outlook email come up large on replies?

When I receive a reply to an email, sometimes part of the email font is very large (about 100pt). It’s just random words/sentences. It doesn’t do it when I create the email, but is just in the reply to me. Then when I reply, it stays large. If there is a table within the email, random lines of the table show up large and dark. It only does it on my Outlook. Please help!