when I will use sfd tag in my question?

Answer 1

SafeForDeletion?
I'm guessing was added for the future thread move tool. For old offtopic posts. So they get moved to your feed when it becomes available. Just a convenience to find them later.

Answer 2

"sfd"??
or "mfd"??
If you mean "mfd" then, please don't use it 😂
It's tagged by mods.
"mfd" means marked for deletion which deletes your question within 24 hours.

Answer 3

sfd not mfd.Look at the questions they used sfd tag:
https://www.sololearn.com/Discuss/452626/?ref=app
https://www.sololearn.com/Discuss/637386/?ref=app
https://www.sololearn.com/Discuss/454060/?ref=app

Answer 4

Just like "mfd" , "sfd" is also added by moderators to your question.
( looking at the fact that all the questions tagged "sfd" are edited by mods)
I actually don't know the reason behind it but if the sololearn moderators follow the same reporting technique as that of wikipedia.com then 'sfd' should probably mean "Stub type for deletion"
Which means the the post(encyclopaedia for wiki) does not contain enough usefull content thus should be removed.
⚠️Note that these are all result of my observations and hence should not be considered as official.⚠️