If you search the web for:
accidentally deleted test prod databaseYou can find myriad stories of people thinking they were looking at the testing/staging deployment of a database or web application, running some destructive operations on it, then realising all too late that they were looking at the production database (the live one with lots of customer data) and phone calls start coming in from users wondering where all the data has gone.
For web front-ends, one trick I’ve used in the past to reduce the changes of such a disaster is a one-line userscript for the test deployment along the lines of:
document.body.style.border = "20px solid red";Depending on your tastes, you might want a similar one in a different colour for the production deployment