Unable to delete other subscribed calendar on iPhone and iPad in iOS18

For some unknown reason, I have a subscribed calendar listed under <Other> in my Calendar app, and I just can’t delete it no matter how I try.

I tapped the ‘i’ icon next to the calendar I want to remove, but there’s no option to delete it.

I also checked Settings >Calendar Accounts, but there’s no account associated with a subscribed calendar.

I even checked on iCloud.com, but this calendar doesn’t show up there. It only appears on my iPhone and iPad.

Is there any way to completely remove this annoying calendar from my iPhone and iPad? I know I can hide it, but I want it gone for good!