The community bot wasn't "turned on" anywhere recently. What's likely happened is that you have a bundle of questions that all qualify but they're all bunched around the same time, so you'll see a handful and then there won't be any or many for a while.
I recently explained how the bot works on MSO:
First it checks the last activity date of open, non-deleted questions to see how recently Community has bumped the question (if ever). The question must be at least 30 days old and can not have been bumped (or otherwise modified) by Community in the last 120 days. This means that a question can only be bumped at most, three times per year.
From that, it selects the top 100 question by views that that meet the following requirements:
- not recently active
- not closed
- not deleted
- score of >=0
- no accepted answer
- is answered and the answer/s:
- are not deleted
- have a max score = 0 (meaning at least one answer must have a score of zero but no answers may have a score >0).
... and then it randomly selects the ones it's going to bump from these 100... In addition, there are other rules that are actually configurable per-site that control how many bumped posts may be on the front page at a time (not set for SO, since the front page moves so quickly) and how many can be bumped per hour (currently 4 on SO).
The settings here are the default - that is there's no value for the max on the front page at any time and it's 1 per hour.
I will quibble with one thing that Joachim said, though:
Finally, here is a list of all the questions that can potentially be bumped.
This is actually the wrong list - that's the list for "no answers" - and if you read my explanation, you'll realize that questions with no answers won't be bumped by Community - the Community bot doesn't care about questions with no answers - it wants people to look at questions with answers that have a score of 0.
To see the ones that Community will actually bump, you'd have to look at the "Unanswered" list (currently 32 items) and ignore any questions with 0 answers (currently 25 from Joachim's link) and only count the items that have at least one zero-score answer. That leaves the following as your "cohort" of eligible questions:
This question is "unanswered" but both answers have a score of -1 so it's ineligible for bumping currently. And this adds up - you have 32 questions on the "unanswered" list minus 25 questions on the "no answers" list and one question that has only negative-scoring answers (32-25-1 = 6).
So, as you can see - you only have six questions that can be bumped as of right now and it likely seems like the bot just got turned on due to three being bumped in the same day - but that's just because those three happen to be on the same schedule. But, as the chart shows, these have been bumped previously. In reality, there just aren't many eligible posts!
Which also means that y'all can easily do something about this!
Go look at those six questions and their answers - are any of the answers worthy of upvotes? Are any of the questions in need of closure? Can you improve answers or add a new answer that might lead to an upvoted or accepted answer? Any of these actions will make the questions ineligible for bumping. Yes, you can also downvote answers but I try not to get overly encouraging of that - the community is richer for good content.
While I'm willing to make it so there's a limit to how many can appear at the same time, that happens once every four months, so I don't really know whether that's the best solution. I've given you a list and explanations of how to address this - the Community bot is doing what it's supposed to do - draw attention to questions with answers that aren't known whether they're good or bad.