Blurry Video After Export

Im trying to export a video I made and it keeps coming out blurry. I've tried using Adobe, Reddit and other websites to fix the issue but nothing helps. The video is 4 minutes long and the footage I've used was an 1920x1080 MP4 file generated by Microsoft powerpoint, with auido clips played over it. I must have exported it in over 20 different ways by now but it still comes out blurry on the three media players I have on my computer, and on media players when moving the exported file to another computer. The file needs to be uploaded to my university website so as long as its not massive the file size doesn't matter too much, I just want a clear image. The output image on the left of the Export Settings window is clear however when exported it is blurry every time. I've included photos. Please help!