LB4 with Loopback-connector-postgresql@5.3.0 causing SSL Error

I kept getting the same error in LB4 even using the right syntax below and right version of loopback-connector-postgresql@5.3.0 after I deploy it to IBM Cloud Kubenetes, it runs without any issues on my local.

import {BootMixin} from '@loopback/boot';
import {ApplicationConfig} from '@loopback/core';
import {RepositoryMixin} from '@loopback/repository';
import {RestApplication} from '@loopback/rest';
import {
RestExplorerBindings,
RestExplorerComponent
} from '@loopback/rest-explorer';
import {ServiceMixin} from '@loopback/service-proxy';
import fs from 'fs';
import path from 'path';
import {ProductSelectionDataSource} from './datasources';
import {MySequence} from './sequence';
export {ApplicationConfig};

export class ProductSelectionApplication extends BootMixin(
ServiceMixin(RepositoryMixin(RestApplication)),
) {
constructor(options: ApplicationConfig = {}) {
super(options);

//process.env['NODE_TLS_REJECT_UNAUTHORIZED'] = '0';
console.log("__dirname: " + __dirname);
console.log("*********************************************************************************");
const crtpath = path.join(__dirname, '../private/ca.crt');
console.log("crtpath:" + crtpath);
console.log("content of crt:  " + fs.readFileSync(crtpath).toString());

console.log("*********************************************************************************");
const keypath = path.join(__dirname, '../private/ca.key');
console.log("keypath:" + keypath);
console.log("content of key:  " + fs.readFileSync(keypath).toString());

console.log("*********************************************************************************");
var dbcert = process.env.DB_CERT;
let dbCert = Buffer.from(`{dbcert}`, 'base64');
console.log("content of dbcert: " + dbCert);

console.log("*********************************************************************************");

this.bind('datasources.config.productSelection').to({
  name: 'dbname',
  connector: 'postgresql',
  url: process.env.DB_CONNECTION_STRING,
  ssl: {
    ca: fs.readFileSync(crtpath).toString(),
    key: fs.readFileSync(keypath).toString(),
    cert: dbCert,
    rejectUnauthorized: false,
  },
});
this.bind('datasources.productSelection').toClass(ProductSelectionDataSource);

// Set up the custom sequence
this.sequence(MySequence);

// Set up default home page
this.static('/', path.join(__dirname, '../public'));

// Customize @loopback/rest-explorer configuration here
this.configure(RestExplorerBindings.COMPONENT).to({
  path: '/explorer',
});
this.component(RestExplorerComponent);

this.projectRoot = __dirname;
// Customize @loopback/boot Booter Conventions here
this.bootOptions = {
  controllers: {
    // Customize ControllerBooter Conventions here
    dirs: ['controllers'],
    extensions: ['.controller.js'],
    nested: true,
  },
};

}
}

The error I got:

Node ENV: dev
Server is running at http://127.0.0.1:3000
Try http://127.0.0.1:3000/ping
Connection fails: Error: self signed certificate in certificate chain
It will be retried for the next request.
_tls_wrap.js:1497

Error: self signed certificate in certificate chain
at TLSSocket.onConnectSecure (_tls_wrap.js:1497:34)
at TLSSocket.emit (events.js:315:20)
at TLSSocket._finishInit (_tls_wrap.js:932:8)
at TLSWrap.ssl.onhandshakedone (_tls_wrap.js:706:12)
at TLSWrap.callbackTrampoline (internal/async_hooks.js:131:14)

I tried to use old version of loopback-connector-postgresql@3.9.1 but it seems the latest version of LB4 doesn't like it. the LB4 version list below:
$ lb4 -v
@loopback/cli version: 2.20.0

@loopback/* dependencies:

• @loopback/authentication: ^7.1.0
• @loopback/boot: ^3.3.0
• @loopback/build: ^6.3.0
• @loopback/context: ^3.15.0
• @loopback/core: ^2.15.0
• @loopback/metadata: ^3.2.0
• @loopback/openapi-spec-builder: ^3.1.0
• @loopback/openapi-v3: ^5.2.0
• @loopback/repository-json-schema: ^3.3.0
• @loopback/repository: ^3.5.0
• @loopback/rest: ^9.2.0
• @loopback/testlab: ^3.3.0
• @loopback/docs: ^3.23.0
• @loopback/example-hello-world: ^2.2.0
• @loopback/example-log-extension: ^2.2.0
• @loopback/example-rpc-server: ^2.2.0
• @loopback/example-todo: ^3.10.0
• @loopback/example-soap-calculator: ^2.5.0
• @loopback/service-proxy: ^3.1.0
• @loopback/http-caching-proxy: ^2.2.0
• @loopback/http-server: ^2.4.0
• @loopback/example-todo-list: ^3.8.0
• @loopback/dist-util: ^0.4.0
• @loopback/rest-explorer: ^3.2.0
• @loopback/eslint-config: ^10.1.0
• @loopback/example-express-composition: ^2.6.0
• @loopback/example-greeter-extension: ^2.2.0
• @loopback/booter-lb3app: ^2.3.0
• @loopback/example-lb3-application: ^2.6.0
• @loopback/example-greeting-app: ^2.3.0
• @loopback/example-context: ^2.2.0
• @loopback/repository-tests: ^0.17.0
• @loopback/health: ^0.7.0
• @loopback/authorization: ^0.8.0
• @loopback/rest-crud: ^0.9.0
• @loopback/security: ^0.4.0
• @loopback/authentication-passport: ^3.1.0
• @loopback/example-metrics-prometheus: ^0.5.0
• @loopback/metrics: ^0.7.0
• @loopback/model-api-builder: ^2.2.0
• @loopback/logging: ^0.5.0
• @loopback/example-access-control-migration: ^2.4.0
• @loopback/example-file-transfer: ^1.6.0
• @loopback/example-rest-crud: ^1.8.0
• @loopback/apiconnect: ^0.6.0
• @loopback/example-validation-app: ^1.9.0
• @loopback/cron: ^0.4.0
• @loopback/example-multi-tenancy: ^0.8.0
• @loopback/example-passport-login: ^1.10.0
• @loopback/authentication-jwt: ^0.8.0
• @loopback/context-explorer: ^0.4.0
• @loopback/express: ^3.2.0
• @loopback/example-todo-jwt: ^1.5.0
• @loopback/mock-oauth2-provider: ^0.2.0
• @loopback/pooling: ^0.4.0
• @loopback/typeorm: ^0.3.0
• @loopback/example-graphql: ^0.2.0
• @loopback/graphql: ^0.3.0
• @loopback/filter: ^1.4.0
• @loopback/rest-msgpack: ^0.4.0
• @loopback/example-binding-resolution: ^0.2.0
• @loopback/example-webpack: ^0.3.0
• @loopback/example-socketio: ^0.2.0
• @loopback/socketio: ^0.2.0
• @loopback/monorepo: ^0.2.0
• @loopback/tsdocs: ^2.5.0

Please advise and thank you so much.

Start with the pasted ProductSelectionApplication constructor and the datasource configuration using loopback-connector-postgresql@5.3.0. Reproduce the SSL failure in the IBM Cloud Kubernetes deployment while comparing it with the local environment, then inspect the connector's PostgreSQL and SSL handling. Done means the cause is identified and a documented, tested configuration or connector fix resolves the certificate-chain error.