Non-native speakers tend to make mistakes with “its” vs “it’s” because they learn that in English the rule for when to after a “subject” put an apostrophe followed by an “s” is when you’re talking about something that subject has, but this case is an exception to that rule since " it " followed " 's " stands for " it is " whilst talking about something that " it " has is written " its ".

I mean, you can memorize there’s an exception to the rule for this case, but if you’re not paying enough attention when writting it’s easy to make a mistake by unthinkingly following the rule as usual even though in this case it doesn’t apply, and even if you re-read the text to check if it’s alright, it’s easy to miss it because you kinda have the right meaning in your mind so you read what you meant to write rather than what you wrote plus they’re both valid forms so neither stands out as a spelling mistake even when misused.