I don't know if I'd call it a misfeature, English does it a lot

It's been forever since I learned any Ukrainian but Ukrainian is a lot more "strict" with their vowel sounds than Russian

о stays an о, unlike Russian where it can become an "ah"

As far as I am aware with Ukrainian it's just е raised towards и (and back again depending on where stress is placed), hence the original comment. Trips up everyone learning Ukrainian