The cosmic rays collide with interstellar carbon, nitrogen and oxygen, breaking them down. When the speeding cosmic ray hits carbon, lithium is produced. Knauth said that they studied two stars in the same interstellar cloud for 50 to 60 hours. They used the star as a light source and monitored how much starlight was absorbed depending on what atoms were in the gas cloud. But we don't see that larger amount.
New stars form inside interstellar clouds.
One possibility is that in an interstellar cloud that's forming these massive stars, these stars then send energy back into the clouds. People have suggested that the production of lithium in a superbubble might explain our observations. But even if the superbubble turns out to be the answer, we might be looking at a rare occurrence.