A faint dragon noise in the overworld

I heard a faint dragon noise in the overworld. It was first a repeated scream/roar sound, then the noise was ended by a different roar. It was like there was a dragon that was dying, like a mob suffocating in a wall. I heard it when I was building a structure next to a ruined portal. I am using Minecraft 1.16. Seed: 1019594688 I was not using any mods or data packs other than Minecraft classic. (The default gameplay of Minecraft)