Ok, real answer is it’s called an iPhone “strap grip”. You can find them on Amazon https://www.amazon.com/Sinjimoru-Silicone-Stretching-Holder-Holder/dp/B08LVBNKR4/ref=mp_s_a_1_1_sspa?crid=1XC2BI4MTXLI3&dchild=1&keywords=iphone+strap+grip&qid=1632059248&sprefix=iphone+strap+&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFOMUxISzYyTTFSME0mZW5jcnlwdGVkSWQ9QTA0MDU3NDQyUVpUNjJWUlJPSlo5JmVuY3J5cHRlZEFkSWQ9QTEwNDQwODA3TlJEQ1lISkJGNUImd2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==