They look like half-width characters. This is a historical issue, not a font style issue. You can check:
https://mailmate.jp/blog/half-width-full-width-hankaku-zenka...
https://mailmate.jp/blog/half-width-full-width-hankaku-zenka...
Realistically it’s only katakana that you can make this mixup on. My desktop IME will let me type カタカナ or (reluctantly) ｶﾀｶﾅ, though it turns out iOS doesn’t have a way to type the half width kana, and IMEs have differing opinions on if they prefer full width digits, so you might see full width numbers like ５０００。