GFZ3 boss invincibility bug

I was doing record attempts again, and before I succeeded I had to save this replay. Among speedrunners this is known as Eggman doing memes. This bug has been in the run attempts for a while but I don't know if you were aware of this, so I'm posting the GIF.

Maybe it's a form of speedrun protecting for Eggman to still be invincible. It could be a coincidence since this is technically the easiest boss in the game.

Or it could be bad timing and that laser hit you before you could hit Eggman. Honestly, the bug isn't clear from the gif if visible at all because you keep getting hit.

It's most likely he's talking about Eggman's infinite dash (before he hits a wall at least) which makes him invulnerable. I had it happen to me quite a few times, too. If it's intended then it's a pretty dumb mechanic, as it's random, which could make speedrunning this boss annoying.

I can try to explain this a little more. In GIF it can look like bad timing. But sometimes when Eggman's invincibility ends and the player is touching him at the same time, it wouldn't take any damage. That's why it mostly happens in speedrunning.

EDIT: It doesn't always happen. Just one of 5-10 hits where you do your hit in the way I told. That's why I think it would actually be a bug.