Byline: Shannon Liao, CNN Business

(CNN) -- In 2018, Twitch streamer Ryann Weller played a 30-second snippet of 50 Cent's "In Da Club" on one of his livestreams. He showed viewers an animated e-card featuring his fans' faces dancing to the 2003 hit song. It became one of thousands of clips that fans have created of Weller's livestreams since he joined the Amazon-owned service in 2015.

"Go shawty, it's your birthday," he rapped to CNN Business, echoing the song's opening line. "I mean, I wish I could show you the clip, but of course it already got deleted."

On June 5, two years after Weller's livestream featuring the 50 Cent e-card and long after he had forgotten it, Weller received a sternly-worded copyright takedown notice via email from Twitch. "We've received a notice of alleged copyright infringement with respect to your account," it said. The copyright claim came from the Recording Industry Association of America, which has ramped up sending takedown notices on Twitch in June.

Weller -- a former game developer for Telltale Games who has nearly 20,000 followers on Twitch -- said he had no idea that videos saved by his fans could make him the target of a copyright infringement claim. Twitch auto-deletes full broadcasts after 60 days, so the clips are all that's left of his old streams.

For years, Twitch has been the Wild West for streaming music, but in recent months it has attracted attention from record labels as its viewership has jumped during the pandemic. In July, Twitch had 1.4 billion hours watched, up 67% compared to the same period last year, with 17.6 million watched in the music category, according to Stream Elements, a publisher of industry reports.

Twitch has fallen under scrutiny by record labels represented by the RIAA, which holds copyrights to millions of songs. In June, the RIAA sent out 1,817 copyright notices to Twitch users. Prior to the June crackdown, only 710 such notices had been issued to Twitch users since the association began sending notices out in 2017.

Is it illegal to stream music on Twitch? Content creators can argue that based on how little music is being used and the context of the stream, some music streaming should be considered fair use and therefore not illegal. But the RIAA said it looks to see if a clip could be fair use before sending out its notices.

On Twitch, users can record highlights from livestreams they watch which are then saved to the streamers' channels. The service operates on a three strike rule. In the first notice, users are warned...