Those kinds of things are done on Bloom filters and maybe you got a false positive.
Try typing tv 6 times in notes app, correcting every time. it should fix itself.
Interesting gif. However, I don't have any problem with "tv" on my iPhone. Maybe something you corrected on the past?
That would have been my thought too but it's a new 6S
In your dictionary someone might have changed an autocorrect from TV to Rv...
Nice! I know that can happen from standard auto-correct usage , it's just that this is a fresh iOS install on a fresh device, I haven't used the word Rv any time lately, and there are definitely no other people who use my phone, and it just started doing it for no reason. Viva la autocorrect!
I wonder if on a fresh install with no previous data to work with if it chooses the word alphabetically? RV does come before TV.