Alayna Fender, a 25-year-old in Vancouver, British Columbia, said she had been bringing in an average of 700 Canadian dollars (approximately $513) from ads on her videos each month, and saw that drop to 130 Canadian dollars in the past month. Ms. Fender, who has about 177,000 subscribers and turned her video-making hobby into a full-time gig a year and a half ago, built much of her audience through frank discussions surrounding mental health and sexuality.

She wanted an explanation for why ad revenue had dried up on her series “I Don’t Bi It” and a video of her describing her lesbian crushes on YouTube, while it had remained steady on videos titled “Top 15 Canadian Stereotypes” and “Bleaching My Hair Blonde.” While YouTube’s guidelines say that “sexually suggestive content” and “sexual humor” are not advertiser-friendly, Ms. Fender said the videos in question were still running ads, but for far less money.

“If they’re going to pull ads from videos without telling us and giving us no notification and no way to appeal it, they need to at least tell us what it is,” she said. “What rules are these videos breaking? What is it that we need to avoid? How can we remain advertiser-friendly? That’s the main problem — the secrecy and how quiet they’re keeping.”

YouTube said in a statement that it had had “lots of positive conversations with advertisers, and many are noticing the improvements we’ve made.”

“While many creators are seeing revenue improvements, some continue to be impacted,” the company said. “We’ll continue to work closely with both advertisers and creators to get things right.”

To replace the ad money, several creators have been turning to Patreon, a crowdfunding site where people can pay them directly by video or per month. YouTube also recently introduced a way for fans to directly support creators through a feature called Super Chat, which allows them to pay to highlight messages they post in live streams. Mr. Wood, of the LiveSciFi channel, said revenue from that feature came close to matching his channel’s estimated ad revenue in April.

He said he was frustrated by a call last week with a YouTube representative.

“She basically told me, ‘Your channel is doing so great, especially for the last month,’ and that everything is up — our numbers are way up, our watch time almost doubled from March,” he said. “But our ad revenue is pretty much a quarter of what it was in March.”