Reverse proxy fail request after failure in jwt parsing - http

Question

I have a reverse proxy, it validates jwt from headers and enriches data,
when an expired jwt arrives the proxy returns an error to the user and status code 502 (with the correct error) - which is good!
After that, every request that arrives with valid jwt is returning an error with message: crypto/rsa: verification error
However, when extracting the jwt from the request and checking it locally I found that everything works perfectly.
The proxy code:
parsedUrl, err := url.Parse("http://localhost:" + environment.ProxyPort)
if err != nil {
log.Fatal(err)
}
proxy := httputil.NewSingleHostReverseProxy(parsedUrl)
proxy.FlushInterval = 200 * time.Millisecond
proxy.Transport = &myTransport{}
proxy.ModifyResponse = func(r *http.Response) error {
return nil
}
proxy.ErrorHandler = func(rw http.ResponseWriter, r *http.Request, err error) {
logs.Log(err.Error(), logs.Error)
rw.WriteHeader(http.StatusBadGateway)
if _, err := rw.Write([]byte(`{"source": "enrich-sidecar", error": "` + err.Error() + `"}`)); err != nil {
log.Fatal(err)
}
}
req.URL.Host = parsedUrl.Host
req.URL.Scheme = parsedUrl.Scheme
req.Header.Set("X-Forwarded-Host", req.Header.Get("Host"))
req.Host = parsedUrl.Host
proxy.ServeHTTP(res, req)
The validation:
if err := validateAlg(jwtToken); err != nil {
return false, nil, err
}
token, err := jwt.Parse(jwtToken, func(token *jwt.Token) (interface{}, error) {
return key, nil
})
if err != nil {
return false, nil, err
} else if !token.Valid {
return false, nil, token.Claims.Valid()
}