The Minecraft Classic texture pack on the marketplace does a great job of bringing the legacy Minecraft textures into the game, but the crying obsidian texture still retained it's texture from 1.16 rather than reverting back to it's legacy texture. This feels like more of an oversight than a bug, but still something that needs addressed nonetheless. I will also be posting on the Feedback site about this issue as well.

That feedback page can be found here: https://feedback.minecraft.net/hc/en-us/community/posts/4414961518733-Legacy-Crying-Obsidian-Texture-for-Classic-Texture-Pack