Unable to add package with protobuf in Yarn monorepo

I am trying to add a new package called ethaccount to the CosmJS monorepo (https://github.com/cosmos/cosmjs). This package is using generated TS protobuf files. The generated protobuf files have the long and protobufjs packages as dependencies, which I have added using yarn add.

The TS protobuf files are placed in packages/ethaccount/dist/proto directory

The following is the tsconfig.json file in my package:

{
  "extends": "../../tsconfig.json",
  "compilerOptions": {
    "module": "commonjs",
    "target": "es2015",
    "declaration": true,
    "esModuleInterop": true,
    "outDir": "./dist"
  },
  "include": [
    "src/**/*"
  ]
}

The package.json for my package is as follows:

{
  "name": "@cosmjs/ethaccount",
  "version": "1.0.0",
  "description": "Exposes EthAccount interface to send txs to Ethermint chain",
  "main": "dist/index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "tsc"
  },
  "author": "",
  "license": "ISC",
  "types": "dist/index.d.ts",
  "files": [
    "/dist"
  ],
  "dependencies": {
    "@cosmjs/proto-signing": "workspace:packages/proto-signing",
    "@cosmjs/tendermint-rpc": "workspace:packages/tendermint-rpc",
    "google-protobuf": "^3.19.1",
    "long": "^5.2.0",
    "protobufjs": "~6.10.2"
  },
  "devDependencies": {
    "ts-proto": "^1.87.1"
  }
}

However, when I try to run yarn build in the ethaccount directory, I get the following error:

dist/proto/cosmos/auth/v1beta1/auth.ts:2:18 - error TS2307: Cannot find module 'long' or its corresponding type declarations.

import Long from "long";
                   ~~~~~~

dist/proto/cosmos/auth/v1beta1/auth.ts:3:17 - error TS2307: Cannot find module 'protobufjs/minimal' or its corresponding type declarations.

import _m0 from "protobufjs/minimal";
                  ~~~~~~~~~~~~~~~~~~~~

Is there something I'm missing here?