This clause means Reddit can commercially exploit everything you post indefinitely, including potentially using your content to train AI systems or for advertising, without paying you or asking for further permission.
Reddit's Terms of Service give the platform a broad, permanent license to all content users post, meaning Reddit can use, modify, and distribute your posts and comments even after you delete them or close your account. Users are also subject to a mandatory arbitration clause and class action waiver, which significantly limits their ability to pursue legal remedies collectively if harmed by Reddit. You can opt out of the arbitration clause by emailing arbitration-opt-out@reddit.com within 30 days of first agreeing to the Terms of Service.