What character can we use as an irony mark?

Irony punctuation – Wikipedia

There have been various proposals over the years, though none have taken off. In internet discourse, where irony marks are pretty necessary, the smiley has prevailed; it’s more about “I’m only joking! I’m only joking!” than about actual amusement.

Some Ethiopian languages use a special temherte slaqî or temherte slaq punctuation for “sarcasm and unreal phrases”, that looks like ¡

Of the Latin alphabet proposals, as Wikipedia enumerates them, there’s been:

⸮

[!]

</sarcasm>

:^)

.~