There have been quite a few punctuations proposed for indicating sarcasm, but interrobang not one of them - that (‽) is literally a combined ? and !, and is (per wikipedia) for "a question in an excited manner, expresses excitement, disbelief, or confusion in the form of a question, or asks a rhetorical question".

This page - https://en.wikipedia.org/wiki/Irony_punctuation - has sarcasm ones (but I don't think any are as well known as the interrobang, which itself isn't exactly universally used... though personally I'm weird enough to have a keyboard shortcut to type it on my phone)

I find all "/s" tags to be offensive to comedy.

Can you imagine "A Modest Proposal (/s)" ?