Calling local dotnet https backend from local NextJS results in FetchError: self-signed certificate

I've recently had to switch my local dotnet core 6 backend development to now run on HTTPS due to some Secure cookies being passed between the backend and the front-end. Unfortunately now I'm having some issues when calling it from my NextJS API which is as follows

error - FetchError: request to https://localhost:5001/api/user/login failed, reason: self-signed certificate

My guess would be that it's because I'm not using https for the next.js local server but I don't fully understand why or how to go about that. Any help either with the solution or understanding the problem would be appreciated. Please find below the problematic code block from my NextJS API.

import type { NextApiRequest, NextApiResponse } from 'next';
import { User } from '../../models/User';

export default async function handler(
  req: NextApiRequest,
  res: NextApiResponse<User>
) {
  console.log(req.body);
  await fetch('https://localhost:5001/api/user/login', {
    body: req.body,
    method: 'POST',
    headers: {
      'Content-Type': 'application/json'
    }
  })
    .then((res) => res.json())
    .then((response: User) => {
      res.status(200)
        .json(response);
      console.log('res', response);
    });
}