By this reading, and since Trump is sworn in on the 20th, it is really up to his discretion as to whether the tiktok ban remains.
He probably should let it stand for a day or two, and then drop an executive order to make it not banned and thus be a hero to all those who use it.
That's not quite correct, b/c the above only applies to companies other than TikTok/ByteDance, which are called out explicitly in the Act.
However, there is an open question as to whether Trump will choose to enforce the law.