I agree on keeping bills separate, but you seem to be confused. Tiktok wasn’t in the same bill, the help for Ukraine, Taiwan and Israel was bundled together.
The reason for it was that the current speaker actually wanted help for Israel and Taiwan but was holding the bill because of Ukraine, which his orange friend doesn’t support.
This is why it was held. Why the speaker had a sudden change of heart?
It was because two Republicans threatened to resign, leaving Democrats in majority and getting speakership (I wish that outcome would actually happened).
So he brought those bills to vote, but he split the bills. Because of it, now they have to go back to Senate, adding another unnecessary delay.