Its back! - The upvote glitch on questions, this time combined with a comment disappearance glitch.

Question

So I know this exists, but its been more than a year since the glitch happened with anyone. Moreover, Y said the glitch doesn't happen anymore; but guess what? Its back!

While viewing this question after logging out which I was viewing when I was logged in, the upvote count on the answer had changed and some comments had disappeared. When I logged in again, the upvote count reverted back to normal and the comments appeared.

Here's a video of the whole glitch:
Video
(Make sure to set the quality to maximum.)

---

For the ones who can't watch the video for some reason, here's the same thing in image format:
While logged out
While logged in - Part 1, Part 2

---

What's with this glitch?
Please don't question my curiosity.
I hope this question is allowed.

Comments

Side Note 1: This happened on 2 browsers on 2 different devices.
Side Note 2: I changed my password after asking this as an extra security measure, so don't worry bout that.
Side Note 3: I had set time to as GMT during recording the video so you can't figure out my location with that. >:)
Side Note 4: If you're wondering why I didn't see any ads, its because of Brave Browser.
Side Note 5: If the title sounds too cheesy then you can change it lol.

---

I believe PM stated somewhere that this is because logged out visitors receive a pre-built webpage that only updates with new information periodically, while logged in users have the webpage built dynamically so that it’s fully up-to-date. This saves time for non-users who likely aren’t going to be a part of the conversation.

---

That would pretty much explain why the glitch happens, but then the question arises: why does it only happen with that question? I tried but it didnt happen with any other question. One could argue that it might be because that question was really old and hadnt been on the activity list for a long time, but then the questions ~Bandit~ and sumwun talked about were recent questions.

Answer 1

For a brief period of time here, I used the site while only being logged out and noticed this happen many times. It was very inconsistent as to which questions it happened with, but it definitely didn't happen with just a single question which I said in the original post.

I am satisfied with Kewl Karl's explanation that this is an integral part of the site and doesn't just "return" from time to time.

Tl;dr: logged out users receive a pre-built webpage that updates with new information only periodically, while logged in users have the webpage built dynamically so that its fully up-to-date.
All credits to Kewl Karl for the explanation.