It looks like the issue with type inference might be related to how the `Effect.Service` is being...

export class SSMClientService extends Effect.Service()("SSMClientService", {
  effect: Effect.gen(function* () {
    const region = yield* Config.string("AWS_REGION");
    /**
     * Retrieves a parameter from SSM Parameter Store with optional decryption.
     */
    const getParameter = (
      Name: string,
      WithDecryption: boolean = false,
    ) =>
      Effect.gen(function* () {
        const ssmClient = new SSMClient({ region });
        const command = new GetParameterCommand({ Name, WithDecryption });
        const parameter$ = yield* Effect.tryPromise({
          try: async () => {
            const response = await ssmClient.send(command);
            return response.Parameter?.Value;
          },
          catch: (e) =>
            new SSMClientError(`Failed to fetch Parameter ${Name}`, {
              cause: e,
            }),
        });
        return parameter$;
      }).pipe(Effect.either);
    return { getParameter };
  }),
}) {}

export class DataFetchingConfigService
  extends Effect.Service()("DataFetchingConfigService", {
    dependencies: [SSMClientService.Default],
    effect: Effect.gen(function* () {
      const { getParameter } = yield* SSMClientService; // type unknown
      const Name = yield* Config.string("AWS_API_APPCONFIG");
      const config$ = yield* getParameter(Name).pipe(Effect.andThen(Either.map(
        (value) =>
          isNotNullable(value)
            ? S.decodeUnknownSync(DataFetchingConfig)(JSON.parse(value))
            : {},
      )));
      return config$;
    }),
  }) {}