VS code show all my hidden lines of code. How can I disable it?

Question

[Problem]

When edit python code in vs code (visual studio code), the editor show all my hidden lines in my code.

[Problem procedure]

(Fig. a) test python code

(Fig. b) I click left blank space of the function name.
Then, I can hide lines of code.

(Fig. c) I type """ in the editor.
Then, the editor automatically add another """ at the end of the line.

(Fig. d) I cut(ctrl+x) automatically added """.
Then, All of my hidden lines are opened. This is the problem.

I call each figures as (a),(b),(c),(d) from left to right

[Question]

I would like to open "my hidden lines" only when I click it.