Adobe Premiere Export Gliches

I exported a video from Premiere with the Adobe Encoder and 5 mins in, it goes pixelated.

So I exported to QT file and then converted to mp4 using Handbrake. This time the image was super crisp but when there was movement, there were lots of narrow horizontal lines - see attached image.

Please can somebody advise me how to export the movies from Premiere without glitches. My expertise is yoga and not editing!

Thank you so much.

Abi

To clarify, first I exported a 15 minute video using the Adobe Encoder with the following settings:
H.264, 1280 x 720, 23.976, CBR, 0.4

It's HD 1080.

I thought everything was fine but the video started to pixelate when there was a radical switch in image (switched camera angle).

I then tried exporting the file as a QT file, Apple ProRes 422. Then I switched to Handbrake and set the average bitrate to 583 to get the file size I am after - which is 80MB. I selected 2-pass encoding and turbo first pass. Which is kind of incidental because the glitches appeared when I exported to QT.

There are a couple of video effects - brightness, white balance, sharpness...

Please can you explain your point about rendering. I have not rendered the files before exporting. I thought that would add an extra hour or so and I am exporting 100 videos. Not that I care about time - only about quality.

One final point, even though the QT file shows glitches as soon as I move, the quality was infinitely better than when I encoded through Adobe.

Narrow horizontal lines means the video wasn't deinterlaced (properly).

At what stage would I deinterlace the video?

You could make Handbrake do it.