If Maiar who served Morgoth were corrupted into Balrogs, then why is it that Sauron, who is also a Maia and servant of Morgoth, didn’t become a Balrog when he pledged his loyalty to Morgoth?

The Maiar exist throughout Tolkien's The Lord of the Rings—Gandalf the Grey (Sir Ian McKellan), Saruman (Christopher Lee), and even the Balrog are ... of the Maiar was Sauron (Charlie Vickers ...

Prime Video’s The Rings of Power revolves around the story of Sauron’s rise as an evil entity and the creation of the rings of power.