This would be best done in After Effects - Assuming that the white line isn't against a particularly complex background.
I'll move this to the After Effects forum for you.
Also have a look at the following guides to help:
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The correction has to be adapted to each image to give a natural render.
Automatic tools like the spot healing brush cannot produce temporally consistent patterns. They don't care for this stuff and their algorithms will calculare a new patch for every stroke. The rest we cannot know for certain without actually seeing a screenshot. If the "rectangle" is merely a thin pixel line, you may not need any brush operations and can do it with simple effects using a few duplicate layers.
Are you still facing this problem? If not, let us know how you solved it. If so, please let us know so we can assist you further.