Make sure these settings are considered before uploading.
Many know that I edit in CapCut.
It's a very simple app. No matter what quality you shoot in, I always export in 1080P and 30 frames per second because these are social media standards.
But there's another trick. Of course, the quality is influenced by the amount of light, how well you can adjust your phone's camera, and color correction. There are many factors, but now you need to check this setting in Instagram itself. Click on the three lines in the top right corner, then go to Settings and Privacy, scroll down and find Media quality, check that the Upload at highest Quality slider is enabled.