Huh, I've not seen this before:

'Despite common misconceptions, 0.999... is not "almost exactly 1" or "very, very nearly but not quite 1"; rather, "0.999..." and "1" represent exactly the same number. '

https://en.wikipedia.org/wiki/0.999...

0.999... - Wikipedia

@fsphil my favorite thing about this page is that it has an arguments subpage on its talk page with years and years of pseudomath https://en.wikipedia.org/wiki/Talk:0.999.../Arguments
Talk:0.999.../Arguments - Wikipedia