I wonder if there was actually a bipartisan majority in favor of getting rid of TikTok?
Yes, the bill passed by a bipartisan majority, but TikTok was not the only thing in that bill. Previous attempts to advance a standalone TikTok bill had failed to get majority support.
This time it got attached to a bill that provided $60 billion in aid for Ukraine, $26 billion in aid for Israel, and $1 billion of additional humanitarian assistance for food, medical supplies, and clean water for Gaza. There was also $8 billion for security in Taiwan and the Indo-Pacific.
A lot of Congress considered that aid (or parts of it) to be critical, and it had taken a lot of time to get there. I bet as a result of that a lot of Congress members would vote "yes" even if they disagreed with the TikTok part.
When Biden signed it he spoke about the importance of all the aid provisions and didn't mention TikTok at all.