A comment's or a reply's note is what its card says. Without it, a comment's card is empty, and a reply renders nothing.
Incorrect
The link expires after
The link expires after :comment[15 minutes]{by="@onmax"}.Correct
The link expires after 15 minutes
onmaxIs 15 minutes enough?.
The link expires after :comment[15 minutes]{by="@onmax" note="Is 15 minutes enough?"}.