The German winger wanted to return to his homeland, and Bayern needed quality on the wings.
But Podolski thinks the 24-year-old still has a lot to learn.
"They get the best players [at Bayern] and Sane is a great player," Podolski told Sky Germany.
"[But] of course he still has further potential.
"He has not yet reached the top level. He still needs a bit more experience, a few more seasons.
"He needs to play regularly with the national team and win a European championship or a World Cup."