Vim copied and pasted content from other places. Why does tab appear after formatting?

  question, vim

Fig. 1, copy the code on a web page, paste it into vim editor, and pressgg=GAfter indenting, a vertical line appears at the front end of line 4, and looking at that distance, it istabThe spacing of the.

Figure 2. Save the content and close it. Open vim again to edit this file. Pressgg=GIndent, the format is normal this time, the leftmost number on line 4 is four spaces.

Why directly copy and paste the contentsgg=GWhat kind of situation will happen?

That’s not a vertical line, that’s vim’s screen is not redrawn, in normal mode,ctrl-lRedrawing the screen.