Honestly I’ve done mostly forgot, and with the proliferation of AI technologies and all the typos AI has read from in the training models, I bet AI isn’t always right about this either.
I usually just don’t care anymore, whether the autocorrect puts the apostrophe in or not.
While it may seem like “it” and “it’s” are different forms of the same word, in reality they are completely different words
he / his
her / hers
It / its
The above are all different forms of the same words.
“it’s” however is merely a shortening of “it is” and on that basis is a totally different word that (very misleadingly!) happens to sound exactly the same as “its”
EDIT:
Another way of looking at this :)
his & he’s (shortening of “he is”) are different words in the same way, but nobody makes the mistake of writing or saying “he’s car” instead of “his car” - it’s obviously wrong because the words sound different - ‘hiz’ and ‘heez’
The same is exactly and identically true of “its” and “it’s’” but those words sound the same, so the mistake comes easily.