The following JWKS from PingFederate causes a parse error. Note that PingFederate is a very common enterprise IdP/SSO, and this error breaks envoy's ability to do OIDC token verification. Lastly, according to the RFC for JWK the "alg" field is optional, and this library shouldn't assuming that the algorithm is "ES256" if missing.
{"keys":[{"kty":"EC","kid":"Ozxgl1WsWyQBF1lcbYyjYl","use":"sig","x":"Vq3vKJCeJyihZIauouQp3eFmuYLCsEcID_sGigAx2gs","y":"3UaPoda-HCrJeU4i960qFHMschTdmqjkitiIyYc5svA","crv":"P-256"},{"kty":"EC","kid":"RBsu7DAEUcrgx4X91TVrsY","use":"sig","x":"dQ_SlIctw4nWZEJ2rasiyrps7jXuxr1E81zw4X-aaY1LLRhcaUxpInytXeZK5mOm","y":"xrhQlZQZeDWm7VRHThevLTKqOkqfNwTmHL7P_f23BPn8SLlXd9p1jS4LzL0KK0rL","crv":"P-384"},{"kty":"RSA","kid":"X3oArm2sGh5pO0jWl5O41C","use":"sig","n":"lOTXC2Pfi0dajzDAOERQLTtT0_GbjAFaNflzV-0tWxban1CPEN0n5UG5z-c0KxKY6fhZshQ1Opr3VbQmE1MGSeYf3qEUD4Th3ZubVV_2Yhuio-UZXllz1EGgAh7sC9TzQi84jIYj_mhdno4l6Y3FVlvM6VtNYRGPDNgjRoVfd63vocXAqgUok6LpEcL9MbrvmK-hFPVNX7euGN_xm_qZM5-JrJMnKz6shnjrul7yZ-ZExzfFx_LSBqum-fkKv2FfEoJqyzyVlbabmDUZ81B9ZP0nfaP3e-IRSQECuXf52PfHqEgZbrax8hKAfpZKJX643gxSCnBWdmNO-BFSlho4pw","e":"AQAB"},{"kty":"EC","kid":"sxG_WeuLxIKXoVit-8vyQf","use":"sig","x":"AG3w2vYgVbn4E27rkxZPUVrzLWhMctY5GOP6xygLLFwNRaoOx2gnlQPwAsEXHxz80u5lfmOms0pJSjuDrNqs5pB4","y":"Ad0K-hbFmTVj3nMOw7jAdl21dlU35pG1g7h_Tswr0VYfxqg4ubIPyXrrtmlKH8q3c2Gqgq77Uq12qfcDE8zF2a4v","crv":"P-521"},{"kty":"EC","kid":"7uLnfLOhXPmOZ2BUaeUue-","use":"sig","x":"fR71QOze0q-0uDBuOyTdJANOA0Kz_WT0ykuuuLH94uCJzD13B5OBB1y4jtOvIYvX","y":"WwjH9z9kzSsGZmkl5BvXhyCO8udP9nNFuZM4WugT7C-kD0UNqojpCEkigWorRlin","crv":"P-384"},{"kty":"EC","kid":"FWwgHZozeidVHog8YEjhT-","use":"sig","x":"C2U_Vuv_t3VEOv-UaprJTir3L_SWq_gjwVSUcLTq5Bc","y":"U9F6c5qlnRLSR_KRiCyAzRk7YUpXrXbqsUJYYlTPw7A","crv":"P-256"},{"kty":"RSA","kid":"aNspNiifg5EiN-R1R-RO4O","use":"sig","n":"klTzMXRM83AWKoKRZQwI5XOdJ0tB0jr1ieo_uLT_W6w_hNY8jbFzN1xwxjyUZFBHQVDU2PlyjRZDKQ5tIRs05__DwCvYdDiN0i5f5ChpB66UkAUn1IuuGUQYP7OHVSdeDCFCq3q8UGrl2FCFRxyL9k9hu0VX7Pj06SNGr74_hbCXF6VJmcgDmoXrTXEC5hSBciauGmAxlIbhDbDx-3QHrPJ5P4OLCwH0kfW2RB50O6DMZmKhXeSqE0WiI9KbMz_Mq-TIMiPNkRC1Wsdv4sKoYHf1t6sdp6n9qconQRGwGZNaWcKk6nno-26a_8CxGAuHh8BIFIvFj5AohFFXu2-slw","e":"AQAB"},{"kty":"EC","kid":"ikc6qm-M_topQoGzydo8zI","use":"sig","x":"AE8C5SEixbzl9ez1NPsYOehpnPohIAMxucjZjw2E9aVCBdGo7t2hKv2Aa7ql4zpeTucrDP3ZyUKK6-D3m3C10ojx","y":"AXNjApqwEKFjFmR4bbxAf_8nS74zDuOtXsq1PnoU58ZcHON1ZBUOEXY0Y6IPw1Q8ngaLHg30I300L1ZL0aIX4ygv","crv":"P-521"},{"kty":"EC","kid":"403dlMPeSjSNp4cQ0GBSLL","use":"sig","x":"AI4FHJCcr7fMCb2BfCj9l6bptD513AVVSbOLP2wPM0Aq6CKOEWlN5Yc8qW1Z8NFOPkjeBsCagV02qNJFxH0oi9em","y":"AK3nxsAk3aMOwqIGU-9xXW2I_wwkRxbTR5cPPceWEzpvUHXqyfOXihVYPTJkbaYggyOWjlpw5RYJZGBTLkFUzdal","crv":"P-521"},{"kty":"EC","kid":"IcGz3uUD_EfbMQWQ-6SrmT","use":"sig","x":"10bDbsUH92XHCizkNtBzumyzro8aZypDTqG6ob1fMXk","y":"zfradNJdJ739STTO9vQmOtMl3r7XlnX2SNEusGsFtz0","crv":"P-256"},{"kty":"EC","kid":"oTrCYqttZBLTIv4R5lrfiZ","use":"sig","x":"kOxZSdBd2DPGjuf0lrV30Bc8LCj2EBMfmluPc3sV44fnsZWtTnQz4pCcDjz2hzOY","y":"587zK_ggKmzpYaKz8AaBKERnAsF0AfLjIo2dAu0BdCO0FzSJGyV_cDpNmAdx8ah4","crv":"P-384"},{"kty":"RSA","kid":"vty_MATEPV9warjejj_hef","use":"sig","n":"6TDzjPXHfjDygJ3wa-0BB4m028hatl-PnfT5BEFcIkkWhGRswQSpiGCGjb3DXQ4LxAwZ_XM5RuBYMOMZw9qEU01lhQycqYVOub7R0lli2oDETW4pOATa6JW7QyyXcbbcnYxqj6qfwKb_XfXBDfLpwT8K1_ylJxAymV1ZgfeXDexGBr7d4fLNzgGV7CjZcYmMftn3CktKrA2vy8fLQ2wfVQgfo1J9UqCmLoo6sorW2Sn23Vsx4sTN8OkcrYzpd8_0Gj0X4jXsnk05rfvAWfn8iBHxe6ERBuVh48SWkGjpRnLLoyFmZFg0d1aDlskWp2rYu0VeeUAfKDAeGAU3_1ihuQ","e":"AQAB"}]}