Invisible & Invulnerable mobs

I've seen some mob which doesn't have texture, hitbox (when F3+B), and cannot be killed/damaged. Morever, the mobs still be able to interact like normal. I found this bug irritating when it affect on a monster. I haven't seen any passive mob got affected by this bug yet because there is no way I can detect those thing, only the monster when they attacked me (like what they are doing from the beginning, but just no texture,.... like above). I first seen this bug in a bastion remnant when an infinite ammount of arrow shooting at me, then I cannot figure what it is until I heard piglin sound. So that I found the bug. Another time, still in nether, I saw a blaze, it go into a room so I follow it to kill it but when arrive, it has gone, then a second later, 3 fire balls hit me from no where, thats when I ran and save my life. The last time I've seen this bug was on enderdragon. It's still normal until he flew down the bedrock structure, then I come to kill him, when I look directly into his head, he dissapear, fortunately, this time I still can hit him, but he just dissapear whenever I look at his head. The back is still fine, he still render well and I still can hit him but that's still a bug which killed me once.

Apparently, I haven't got any clip/picture because I was too panic to escape those troubles, but if I seen it again, I will record it