Why aren't my hyperlinks blue or underlined when composing emails?

It used to be that when I added a hyperlink to my Mac Mail emails, the link would show as blue and maybe even underlined. Now, there is no indication that there is a link, other than my recipient knowing to hover over the word. For example, if I want to tell someone in an email, "Go to the Apple website," I can insert a link over the word 'Apple' but 'Apple' won't be blue or underlined. (Weirdly I can easily do that in this forum! Apple.) Here's how it looks with a hyperlink in Mail but ONLY when you hover over it:

I sometimes try to change the font color from black to blue, but often that then deletes the link! Would love to know what setting was changed and how to get that back. iOS is updated, I've re-started, and this has been an issue for a number of months. Thanks for any guidance.