I had a friend in for the UGA game and over the course of 5 days we were in a bunch of restaurants in Austin, and every one of them was using Toast. It was startling so I bought TOST calls right before their last earnings and scored a quick double up. All of that to say, if your thesis is that TOST is taking market share from SQ( which I agree with), you might want to consider a bet on TOST instead of a bet against SQ.
TOST is about 4-5 times smaller than SQ in market cap and isnt going to take share away from all of SQ's businesses. As an example, Cash App is growing fast for SQ and is a bigger part of the total company gross profit than the SQ platform($1.3B vs $.93B last quarter). SQ has some exposure to the BTC market through Cash App which might distort their short term financials as well with the recent crypto euphoria. Just a thought.