https://www.subarupartsdeal.com/parts/subaru-sun-visor-assembly-left~92011fg030me.html

Looks like you have to buy a whole new visor, as that piece is not sold separately

Edit: this is the part I bought off Amazon that was cheaper than the above option. https://www.amazon.com/dp/B07ZFPM7BK/ref=cm_sw_r_cp_api_glc_fabc_Hzr-FbGAXQED6?_encoding=UTF8&psc=1

While it is 10 bucks cheaper, the overall build is entirely plastic (compared to the OEM being more plush feeling) and the slider for the mirror catches when you open or close it. Up to you