It's easier than ever to de-censor videos

My Windows-98 approved method for redacting a screenshot:

1) Open screenshot in MS-Paint (can you even install MS-Paint anymore? Or is it Paint3D now?)

2) Select Color 1: Black

3) Select Color 2: Black

4) Use rectangular selection tool to select piece of text I want to censor.

5) Click the DEL key. The rectangle should now be solid black.

6) Save the screenshot.

As far as I know, AI hasn't figured out a way to de-censor solid black yet.

There was a programming competition, can't remember which, similar to IOCCC but more about problematic software? where the redaction was reversible despite being pure black, due to the format chosen allowing for left over information in the image (vastly reduced quality but it was enough to allow text to be recovered!) [edit: see replies!]

There was also the Android (and iOS?) truncation issue where parts of the original image were preserved if the edited image took up less space. [edit: also see replies!]

Knowing some formats have such flaws (and I'm too lazy to learn which), I think the best option I think is to replace step 6 with "screenshot the redacted image", so in effect its a completely new image based on what the redacted image looks like, not on any potential intricacies of the format et al.

You are thinking of John Meacham’s winning entry in the 2008 underhanded C contest https://www.underhanded-c.org/_page_id_17.html