だというのに

even though

→ だ
phrase Rare #36,860
even though Expresses a strong contrast, often with surprise, disappointment, or criticism. It is often equivalent to “and yet” or “despite the fact that.”
JA: もう春だというのに、まだ雪が降っている。
EN: Even though it's already spring, it's still snowing.

決戦前夜だというのになぜ

Why, of all times, on the eve of the decisive battle?

— ロード・オブ・ザ・リング/王の帰還 (2003)

留守だというのに不思議なことに中の電灯ついていた

Strangely, all the lights in the house were on, even though everyone was away.