You were directed to their website from a Social Media post or a website advertisement for a free Astrology reading. In the fine print it also noted that the free reading was a free trial for a subscription if you do not cancel. The subscription is not being managed by Apple, which is why you will not find it in your settings. The website is billing your card directly.
What card do you have that is being billed?
You may be able to find out more information here:
https://help.hint.app/hc/hint-help-center/articles/1722517688-how-do-i-cancel-my-subscription
Their refund policy is available here:
https://help.hint.app/hc/hint-help-center/articles/1722517666-refund-policy
Other help topics are available here:
https://help.hint.app/hc/hint-help-center/en