Tools like pluto-for-channels or pluto_tv_scraper on GitHub are the gold standard for this. They run a tiny web server on your home network (or a PC) that talks to Pluto TV, gets a fresh token, and hands it to your IPTV player.
If you have a local M3U file that is only partially broken, you can try to verify the streams using VLC. pluto tv iptv m3u playlist fix
Modern Pluto TV streams now use a JWT (JSON Web Token) . gets a fresh token