TempDB automatically re-uses space. So, if the transaction log continues to grow it is because it has rows which may not be deleted due to open transactions.

I have found that...

I guess this is another example of why we have recommended for years not to use the syntax SELECT *

Dude!

This is a feature of TSQL we have utilized to great advantage for years.

You are using set logic to implement the impact of each row upon an already existing variable.

I...