Hi, this isn't actually a generation glitch. What you've found here is an "ore vein". These are very large, snake-like underground ore formations that contain a bunch of ores. I loaded up a world with the seed and coordinates you've provided to show you how these look when not surrounded by stone/deepslate/gravel, etc... The raw block of iron shown within the lower right of the screenshot indicates that this is an iron ore vein. This is an intentional generation feature. 
MC-239093 - Analysis.png
Hi, this isn't actually a generation glitch. What you've found here is an "ore vein". These are very large, snake-like underground ore formations that contain a bunch of ores. I loaded up a world with the seed and coordinates you've provided to show you how these look when not surrounded by stone/deepslate/gravel, etc... The raw block of iron shown within the lower right of the screenshot indicates that this is an iron ore vein. This is an intentional generation feature.

MC-239093 - Analysis.png