Video in square pixels

Hi, sometimes my videos are heavily pixelated when editing, such as when the bitrate is low, and if you export the video, these pixels will remain, but there is no such thing in other video editing programs. Is there any way to fix this?

https://i.imgur.com/AKZL5Xh.png

Which codec? Which kind of source? Which GPU?

Without enough pixels, you will always get blocking, such as you appear to being experienced. As already suggested, knowing more about the pixel dimensions of your frame, the CODEC, and the overall bit rate you are trying to work with it is hard to make any kind of recommendation.

A little reading about how digital imaging works may help. This is not a situation where there is a cookbook approach. Part of pre-shoot planning for what you will be shooting with, and what your deliverable will be is essential

If that's really important footage, give Tops Labs' Video AI a try. It can cure some of such problems.