Throughout the series so far, Galadriel has been hunting for Sauron, the Dark Lord her brother died trying to take down. But has Sauron been under her nose this whole time, disguised as Halbrand?
CNET lists some evidence against him. Halbrand says he is running from a dark past, for example, and his bloodline traces back to servants of Morgoth, Sauron’s now-defeated boss. Halbrand is also very charismatic, the site argues, and he’s a surprisingly brutal fighter.
Source: https://www.distractify.com/p/is-halbrand-sauron-rings-of-power