A password is hashed with a fast general-purpose digest (MD5, SHA1, SHA256, SHA512) from System.Security.Cryptography.

using System.Security.Cryptography;
using System.Text;

public class Accounts
{
    public byte[] HashPassword(string password)
    {
        // ruleid: auth.csharp.crypto.weak-password-hash
        return SHA256.HashData(Encoding.UTF8.GetBytes(password));
    }

    public byte[] LegacyHash(string password)
    {
        // ruleid: auth.csharp.crypto.weak-password-hash
        return MD5.HashData(Encoding.UTF8.GetBytes(password));
    }
}

using Microsoft.AspNetCore.Identity;
using System.Security.Cryptography;
using System.Text;

public class Accounts
{
    private readonly PasswordHasher<object> _hasher = new();

    public string HashPassword(object user, string password)
    {
        // ok: dedicated slow, salted password hasher
        return _hasher.HashPassword(user, password);
    }

    // ok: SHA256 over a file, not a password
    public byte[] Checksum(byte[] fileBytes)
    {
        return SHA256.HashData(fileBytes);
    }
}