Hi ch-redd,
Welcome to Apple Support Communities. We understand that you're attempting to set up a keyboard shortcut on your Mac, but you're not getting the desired result.
Based on your post, the feature being triggered is known as Spoken Content. You can read more about that here: Have your Mac speak text that’s on the screen As mentioned in that article, you can disable this feature by deselecting "Speak selection" under Apple menu > System Preferences > Accessibility > Spoken Content.
The support articles below can also help with ensuring your shortcut functions as expected.
Create keyboard shortcuts for apps on Mac
If a keyboard shortcut doesn’t work on Mac
Let us know if this information helps with your issue.
Regards.