Learned something new today:
A box spread is an options arbitrage strategy that combines buying a bull call spread with a matching bear put spread.
www.investopedia.com
This appears to be the most substantial risk for this trade (from above link):
"A second potential danger, which is perhaps less obvious, is the risk of early exercise.
American style options, such as those options listed on most U.S. stocks may be
exercised early (i.e., before expiration), and so it is possible that a short option that becomes deep in-the-money can be assigned. In the normal construction of a box, this is unlikely, since you would own the deep call and put, but the stock price can move significantly and then find yourself in a situation where you might be
assigned.
This risk increases for short boxes written on single stock options, as was the
infamous case of a Robinhood trader who lost more than 2,000% on a short box when the deep puts that were sold were subsequently assigned, causing Robinhood to exercise the long calls in an effort to come up with the shares needed to satisfy the assignment. This debacle was posted online including on various subreddits, where it has become a cautionary tale (especially after said trader boasted that it was a virtually riskless strategy)."