This is only observed on Safari Version 15.6 (17613.3.9.1.5); Firefox seems to render as expected.
Observe the following via the Tailwind playground:
https://play.tailwindcss.com/CBCrf9Ujbt
The above has scrollable space on the x-axis. Now if we remove the long comment, observe the drop-shadow disappear:
https://play.tailwindcss.com/74dWNJOG0k
Why is this happening and how can we work around this such that the drop-shadow displays consistently?