Kubernetes ingress error on SAML auth

[error] 1904#1904: *29000294 upstream sent too big header while reading response header from upstream, client: <IP>, server: ~^(?<subdomain>[\w-]+)\.auth-dev\.server\.net$, request: "POST /ui/login/login/externalidp/saml/acs HTTP/2.0", upstream: "grpc://10.224.2.168:8080", host: "test-organization.server.net", referrer: "https://mocksaml.com/"

  ingress:
            enabled: true
            className: nginx
            annotations:
              nginx.ingress.kubernetes.io/ssl-redirect: 'true'
              nginx.ingress.kubernetes.io/backend-protocol: 'GRPC'
              nginx.ingress.kubernetes.io/client-body-buffer-size: 64k
              nginx.ingress.kubernetes.io/client-header-buffer-size: 100k
              nginx.ingress.kubernetes.io/http2-max-header-size: 96k
              nginx.ingress.kubernetes.io/large-client-header-buffers: 4 100k
              nginx.ingress.kubernetes.io/proxy-body-size: 150m
              nginx.ingress.kubernetes.io/proxy-buffer-size: 96k
              nginx.ingress.kubernetes.io/proxy-read-timeout: "1000"
              nginx.ingress.kubernetes.io/proxy-send-timeout: "1000"
              nginx.ingress.kubernetes.io/server-snippet: |
                client_header_buffer_size 100k;
                large_client_header_buffers 4 100k;
                grpc_buffer_size 16k;
...