The in-app description also says, "You can earn money by running short ads on your IGTV videos. When you monetize on IGTV, you agree to follow the Partner Program Monetization Policies."
IGTV currently has a low usage rate, but that might change soon with monetization coming in, which should lure content creators to the platform, enabling them to generate additional income from the struggling platform. And as you know, IGTV's monetization option discouraged creators from adopting the platform as they see no business case in uploading content to IGTV.
While there is no definite timeline for its rollout, IGTV could see growth this year.