I have a similar issue with this, the URL has my domain name, but "test" after the dot as in https://www.mydomainname.test/wc-api/WC_Gateway_Paypal/ . As above, PP payments work normally, but I keep getting these emails from PP saying "IPNs sent to the following URL(s) are failing." Of course they are failing but I don't know how to fix this.
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