Wondering how is this possible?

Last night, watching Manie-Manie 迷宮物語(manie-manie meikyū monogatari) I’ve noticed a thing that drove me mad. On the helmet of a droid in the last episode there’s a inscription that says “安全第一” So far,
nothing too fancy: it’s just a common phrase
to find, especially on a working site
environment. The thing is, 第 is written in
what is likely to be simplified form. Fun fact:
this kanji doesn’t exist. I didn’t find anything
about this, neither in Japanese or in Chinese.
Am I too stupid to found the missing kanji, or
there’s something I miss? Pic related (https://
twitter.com/animegolem/status/
1198967206744412161?s=21)