Failed curl request mashlol/notify backend

curl.log

*   Trying 2a00:1450:400e:808::200e...
* TCP_NODELAY set
* Connected to us-central1-notify-b7652.cloudfunctions.net (2a00:1450:400e:808::200e) port 443 (#0)
* ALPN, offering h2
* ALPN, offering http/1.1
* successfully set certificate verify locations:


} [5 bytes data]
* TLSv1.2 (OUT), TLS handshake, Client hello (1):
} [241 bytes data]
* TLSv1.2 (IN), TLS handshake, Server hello (2):
{ [100 bytes data]
* TLSv1.2 (IN), TLS handshake, Certificate (11):
{ [8122 bytes data]
* TLSv1.2 (IN), TLS handshake, Server key exchange (12):
{ [300 bytes data]
* TLSv1.2 (IN), TLS handshake, Server finished (14):
{ [4 bytes data]
* TLSv1.2 (OUT), TLS handshake, Client key exchange (16):
} [37 bytes data]
* TLSv1.2 (OUT), TLS change cipher, Client hello (1):
} [1 bytes data]
* TLSv1.2 (OUT), TLS handshake, Finished (20):
} [16 bytes data]
* TLSv1.2 (IN), TLS handshake, Finished (20):
{ [16 bytes data]
* SSL connection using TLSv1.2 / ECDHE-RSA-CHACHA20-POLY1305
* ALPN, server accepted to use h2
* Server certificate:
*  subject: C=US; ST=California; L=Mountain View; O=Google LLC; CN=misc.google.com
*  start date: May 14 13:38:45 2019 GMT
*  expire date: Aug  6 13:20:00 2019 GMT
*  subjectAltName: host "us-central1-notify-b7652.cloudfunctions.net" matched cert's "*.cloudfunctions.net"
*  issuer: C=US; O=Google Trust Services; CN=Google Internet Authority G3
*  SSL certificate verify ok.
* Using HTTP2, server supports multi-use
* Connection state changed (HTTP/2 confirmed)
* Copying HTTP/2 data in stream buffer to connection buffer after upgrade: len=0
} [5 bytes data]
* Using Stream ID: 1 (easy handle 0x5636c7980900)
} [5 bytes data]
> GET /sendNotification?to=AcTuAlKeYhIdDeN&text=TEXT&title=TITLE HTTP/2
> Host: us-central1-notify-b7652.cloudfunctions.net
> User-Agent: curl/7.58.0
> Accept: */*
> 
{ [5 bytes data]
* Connection state changed (MAX_CONCURRENT_STREAMS updated)!
} [5 bytes data]
< HTTP/2 429 
< content-type: text/plain; charset=utf-8
< x-content-type-options: nosniff
< x-cloud-trace-context: 05f6058b145c1faaf126875991715598
< date: Tue, 04 Jun 2019 13:56:17 GMT
< server: Google Frontend
< content-length: 36
< alt-svc: quic=":443"; ma=2592000; v="46,44,43,39"
< 
{ [5 bytes data]
* Connection #0 to host us-central1-notify-b7652.cloudfunctions.net left intact
Error: could not handle the request