Guren no Yumiya (OP1) had it in the lyrics all along.. : r/titanfolk

Attack on Titan S1 Op Theme - Linked Horizon - Guren No Yumiya (Lyrics & 432Hz)

Attack on Titan All OPs and EDs analyzed for AoE evidence : r/ANRime

A lot of English covers of Guren no Yumiya have different lyrics than the subtitles in the show. Here are the lyrics the show gives with a few extra things I added

Guren-No-Yumiya (Attack on Titan) Sheet music for Piano (Solo)

Attack on Titan / Shingeki no kyojin - Season 3 (Part 2) Episode 1 (or S3E13, or just Episode 50) - The Town Where Everything Began - Discussion : r/titanfolk

Attack on Titan - Guren no Yumiya 【English Dub Cover】Opening Song by NateWantsToBattle

Attack on Titan - Guren no Yumiya (Opening), ENGLISH ver

Attack on Titan / Shingeki no kyojin - Season 3 (Part 2) Episode 1 (or S3E13, or just Episode 50) - The Town Where Everything Began - Discussion : r/titanfolk

Anime Lyrics - Attack On Titan Opening 1- Guren no Yumiya - Wattpad