What the Gutenberg?
Gutenberg is the code name for the new WordPress post editor. It was included in version 5.0 of core, but is still its own project that gets periodically merged into major and minor (but not patch) updates. However, there is no correlation between Gutenberg and WordPress core versioning, nor is there any indication in core's code about which Gutenberg version has been included. This makes it very difficult to figure out what version of Gutenberg is in which version of core.
The obfuscation is likely purposeful, but sometimes it is useful to have this information. Well, I find it helpful. If you do too, here you go. This is a manually curated list of Gutenberg versions to Core versions, starting from 5.3 because I do not really care to go backwards from there.