The use as a complimwnt or insult has changed over time.

It was once a positive about being yourself (unique).

Then it conservatives used it to refer to someone thinking they were special.

Then it was used to mean someone who melted at any criticism, generally referring to conservatives who thought they were special because they ‘know something everyone else didn’t’ (Qanon morons).

When conservatives all someone a snowflake and when people call conservatives snowflakes the insults are slightly different.