I regularly scan the Stack Exchange front page for interesting questions. It looks like among all the sites Code Golf has been overrepresented for a long time, and right now it got kind of weird: five out of the top ten (and four out of the top five!) questions on the front page are from Code Golf. Is there some weighting that's gone wrong, or is Code Golf really by far the most popular of the Stack Exchange sites?
I think Code Golf just lends itself very well to having hot questions. Answers are taken into account when calculating the hot network questions score:
(MIN(AnswerCount, 10) * QScore) / 5 + AnswerScore ------------------------------------------------- (QAgeInHours + 1) ^ 1.4
On Code Golf, there will generally be many answers because each language gets its own answer. So, every answer up to a maximum of 10 answers will make sure the posts from Code Golf get a little boost in hotness score. Add in some active voting and you have a recipe for hot posts. So the weighting isn't wrong, these posts really are the hottest at the moment. There are other sites that often reach HNQ because of the amount of answers and votes a post gets, like Worldbuilding or The Workplace.
To prevent overrepresentation though, each site can only have a maximum of 5 posts in the HNQ list at a time. And sites can ask Stack Exchange to lower that number, for example when they feel the amount of posts in the HNQ at any time put an unwelcome burden on community moderation work on their site. But this is something that needs to be discussed by the people active on that site, not by people that are just getting tired of seeing the site's questions on HNQ.
What's going on here boils down to two things:
- The questions on that site invite many answers per question
- The community is very active with voting
This leads to questions with high scores in the formula that determines which questions appear in the Hot Network Questions list. If we wouldn't have a maximum of five questions per site in the list, there surely would be more of them in the top regions. Some sites are penalized, which is an old way of making sure not too many questions would appear in the list, but I guess that wouldn't matter here. See, not many people are browsing the Hot Network Questions the way you do; most traffic comes from the widget in the right sidebar, and the questions shown there are randomly chosen from the top 100; the top 10 isn't shown more often than the bottom 10.
Actually, I'm not even sure Code Golf is the most 'popular' site when it comes to Hot Network Questions. A few years ago, it used to be Worldbuilding; here is some research I did back then. Code Golf was already number one when it comes to % of questions which become hot. When I have time, I'll have a look at updating that list with figures from 2020.
"is Code Golf really by far the most popular of the Stack Exchange sites?"
It's not the most popular.
Consider these numbers which you can see here:
Sites with most questions/day in the last 14 days:
Code Golf has 3.6/day
Sites with most visits/day:
StackOverflow: about 11 million/day
SuperUser: about 761 thousand/day
Code Golf has about 6000/day
Sites with most users:
StackOverflow: about 14 million
SuperUser: about 1 million
Code Golf has about 81 thousand.
"Are Code Golf questions overrepresented on the front page?"
The other answers have given a formula that approximates how the HNQs are determined. Keep in mind that the real formula for this is not publicly available, but the main point is true, which is that the number of answers on a question has a big impact.
With Code Golf (and some of the other sites that get a lot of HNQs), the questions do not have just "one authoritative answer" but they invite several people to answer. At Code Golf, right now there's 124 answers across their 5 Hot Network Questions! This makes it much easier for them to get in the HNQ list than sites where, for example, Mathematica.SE where people tend to ask how to do something in Mathematica and there's sometimes only one answer to the question.
Is Code Golf over-represented in the HNQs list?
Along with others like World Building and The Workplace, their questions do tend to get into the HNQ list easier. Perhaps the part of the HNQ formula which contains a multiplication factor by the number of answers to the question, can be damped by the site's overall question-to-answer ratio! I don't see that causing any serious problems that are bigger than any of the problems that currently exist. But keep in mind that there will never be a "perfect" formula for scoring the "hotness" of questions. Another foible with the formula is that the chances of a question appearing in the HNQ list decays exponentially with the time that's passed since the question was asked, which makes it unfair for sites where very difficult questions get asked (where the average time to get an answer is longer than 3 days, for example).
 My answer shows some examples of the HNQ formula failing: Questions with a lower score from the formula, appear as HNQ over questions with a higher score, despite taking into consideration all caveats of the formula such as the maximum of 5 questions/site and the known penalties (site's that appeared to be penalized in one experiment seemed not to be penalized in the next experiment, for example), etc.