If you are playing under the Japanese locale and your opponent cast Three Steps Ahread, a spree instant, MTG Arena always highlights all three modes (i.e., no modes are grayed out) on the stack regardless which modes the opponent chose. Of course, you could know the chosen modes by examining which lands were tapped to cast it or whether it was targetted (and what is the target if any), but it is very inconvenient (and can be a big handicap) for Japanese-speaking players.

The behavior may be common to all spree cards (or even to non-spree modal cards), though I'm not sure. I'm sure I often see my opponent casts Three Steps Ahead and the UI behaviour for the card has the problem, but I don't remember what happened when my opponents cast other modal spells. Perhaps I have not experienced difficult moments by other cards that more than one mode is reasonable to be cast and whether I should respond to it depends on the chosen modes...

(By the way, I usually play under the Japanese locale, and I've been thinking that this behavior is a feature of MTG Arena common to all languages. I recently knew that MTG Arena tells chosen modes explicitly to English-speaking players when watching an English-speaker's streaming).

Steps to reproduce the bug

1. Run MTG Arena under the Jaspanese Locale (Adjust Options > Graphics > Locale > 日本語 (Japanese). You may need to exit and restart the game for the change to take effect.)
2. Play against a deck containing Three Steps Ahead.
3. Keep playing until your opponent casts Three Steps Ahead with one or two (not three) modes.

Platform

PC (Windows 11 Pro 24H2 build 26100.3194)

Actual results

No modes of the Three Steps Ahead on the stack are grayed out.

Expected results

Unchosen modes are grayed out.

Relevant screenshots/videos

See the attachment. It is a screenshot of the moment that my opponent cast Three Steps Ahead (三歩先), choosing the first and third modes.

Also note that all three modes of Three Steps Ahead are packed in a single paragraph. I filed it as a separate bug in https://feedback.wizards.com/forums/918667/suggestions/49217225

Workaround

I don't know.