That's hardly Apple's fault. In app purchases that resolve around items are invariably hard to dispute.
Sorry to say but this is more down to you not locking the device down than it is Apple's fault.
They provide processes to prevent this for a reason.
Prevent in-app purchases from the App Store
You can use Screen Time to prevent unintentional or unauthorized purchases from the App Store and other Apple services. You can require a password for purchases, prevent certain types of purchases, or disable purchasing completely.support.apple.com
yes i have had the device for seven days had it set up for a child, it asked for my password for a purchase, i didn’t realize it wouldn’t ask again for 15 minutes. i go to the bathroom and come back to my bank account drained. you would think a company as big as apple, that i have been loyal to for years, would do the decent thing and refund at the very least a portion, but no i get to say sorry there’s no electric kids but hey! we have pokecoins for dinner!