Hi arielv101, are you having this problem on the Outlook website (for example https://outlook.office.com/) or in the locally installed Outlook that is part of Microsoft Office?

Assuming it is the website, are there any others where you noticed reversed text?

thanks! it's locally installed, but attached another example. this is when i right click on the mouse in the toolbar area

I don't know whether Firefox is incompatible with your Windows theme, or your graphics card driver software, or both, or neither. But let's start here:

Could you switch Firefox from the "Default" theme to the "Light" theme. You can do that on the Add-ons page, or via Customize, as described in this article: Built-in themes in Firefox - alternative to complete themes.

Could you try disabling Firefox from using hardware acceleration? This is a potential workaround for incompatibilities between Firefox and your graphics card/chipset driver software. This article describes where to make that change: Firefox's performance settings. This will take effect the next time you exit Firefox and start it up again. Any difference?

Since hardware acceleration improves the appearance of fonts and animations, you may want to check whether graphics card/chipset driver updates are available for your system. This article suggests safe ways to do that: Upgrade your graphics drivers to use hardware acceleration and WebGL.