When you copy a block of text, it doesn't record the absolute number of tabs at the start of the line, but how many it has relative to the first line of code. And when you paste the text, it keeps the number of tabs relative to where the first line gets pasted.
ie: line 2 of copied text has 1 less tab than line 1, so when you paste it, it has 1 less than where line 1 is.
ie: line 2 of copied text has 1 less tab than line 1, so when you paste it, it has 1 less than where line 1 is.