When running the OWASP dependency check in a project with okhttp in its dependencies the OWASP check finds the following two vulnerabilities:
kotlin-stdlib-1.3.71.jar: CVE-2020-29582
kotlin-stdlib-common-1.3.70.jar: CVE-2020-29582
According to the NVD (link to CVE-2020-29582) the fix should be present in version 1.4.21 onwards.
The two libraries are used by Okhttp from Squareup.
Feign Okhttp 11.6 uses Okhttp (Squareup) 4.6.0 (April 2020). So this could have already been fixed in Okhttp.