Could it be that server certificate has been renewed, but that the root (and/or optionally the intermediate certificate) on your server has expired? Your Chrome browser will also have already its own recent version of that root CA certificate. So he is not interested in the old root cerificate that your server offers.
On the other hand the http request node probably hasn't got a recent version of that root certificate, so the node has to use the old expired root certificate that your server sends to him in the ssl handshake. So he will compkain that the root certificate is expired
Could that be possible?
If so, I think you can solve it:
Best by importing a recent root certificate in the keystore of that server.
If you don't own that server, I assume you can import a recent root certificate on your system where Node-RED runs, so the http request node uses that one? Not sure because I haven't used that yet...