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.
I did though, under certain circumstances. Microsoft's Snipping Tool was vulnerable to the "acropalypse" vulnerability - which mostly affected the cropping functionality, but could plausibly affect images with blacked-out regions too, if the redacted region was a large enough fraction of the overall image.
The issue was that if your edited image had a smaller file size than the original, only the first portion of the file was overwritten, leaving "stale" data in the remainder, which could be used to reconstruct a portion of the unedited image.
To mitigate this in a more paranoid way (aside from just using software that isn't broken) you could re-screenshot your edited version.