Firefox is automatically downloading EVERY pdf I open for reading DESPITE my Settings overriding this.

I recently noticed that EVERY pdf I open for reading is being saved in my computer's Downloads folder! '''DESPITE '''my Settings "Ask where to save files before downloading" and "Ask to open or save files." I am enrolled in an online certification program: There is LOTS of reading. LOTS of information being shared through the class portal. I just discovered this mess a couple of weeks ago. Today, I added a check mark to Other Files under Settings: "Delete private window downloads on close." I'm hoping this will resolve the problem. Am I missing something??? WHY is my longtime browser doing me like this? FYI: I'm using the Windows 11 OS on my six-year-old laptop. My Firefox (152.0.5) stays current.