The words aren’t the trick — the weight is. Equal choices should look equal, because in an interface visual hierarchy is perceived importance. When “keep” is a fat filled button and “cancel” is 11px of grey text, the screen has already voted for you before you’ve read either one. That’s a false hierarchy, and its usual travelling companion is confirmshaming — making the exit say something like “No, I don’t want to save money,” so leaving feels like admitting a character flaw. You don’t have a character flaw. You want to cancel.
The pattern underneath both is the Roach Motel: subscribing is one joyful tap; leaving is a corridor — a chatbot, a “we’ll miss you,” a phone number open weekdays only. None of it is an accident and none of it is hard to fix.
The fix is 30 years old and takes zero engineering: symmetry. If joining takes one tap, leaving takes one tap, and the button just says Cancel. The design word Nielsen used in 1994 is a clearly marked emergency exit. Anything more asymmetric than the way in isn’t a UX problem — it’s a business decision wearing a UX costume.