Proof-of-concept fix for https://github.com/dotnet/aspnetcore/issues/17999

aspnetcore-validationerror-jsonnaming.cs

// Usage: in Startup.ConfigureServices, add:
//   services.AddSingleton<IConfigureOptions<MvcOptions>, JsonPropertyMetadataProviderSetup>();

using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ModelBinding.Metadata;
using Microsoft.Extensions.Options;

public class JsonPropertyMetadataProviderSetup : IConfigureOptions<MvcOptions>
{
    private readonly IOptions<JsonOptions> _jsonOptions;

    public JsonPropertyMetadataProviderSetup(IOptions<JsonOptions> jsonOptions)
    {
        _jsonOptions = jsonOptions;
    }

    public void Configure(MvcOptions options)
    {
        var namingPolicy = _jsonOptions.Value.JsonSerializerOptions.PropertyNamingPolicy;
        options.ModelMetadataDetailsProviders.Add(new JsonPropertyMetadataProvider(namingPolicy));
    }
}

internal class JsonPropertyMetadataProvider : IBindingMetadataProvider, IDisplayMetadataProvider
{
    private readonly JsonNamingPolicy _jsonNamingPolicy;

    public JsonPropertyMetadataProvider(JsonNamingPolicy jsonNamingPolicy)
    {
        _jsonNamingPolicy = jsonNamingPolicy;
    }

    public void CreateBindingMetadata(BindingMetadataProviderContext context)
    {
        if (context.BindingMetadata.IsBindingAllowed && IsNonControllerProperty(context.Key))
        {
            var jsonPropertyName = JsonPropertyName(context.Attributes, context.Key);
            context.BindingMetadata.BinderModelName ??= jsonPropertyName;
        }
    }

    public void CreateDisplayMetadata(DisplayMetadataProviderContext context)
    {
        if (IsNonControllerProperty(context.Key))
        {
            var jsonPropertyName = JsonPropertyName(context.Attributes, context.Key);
            context.DisplayMetadata.DisplayName ??= () => jsonPropertyName;
        }
    }

    private static bool IsNonControllerProperty(ModelMetadataIdentity key) =>
        key.MetadataKind == ModelMetadataKind.Property
        && !key.ContainerType.IsAssignableTo(typeof(ControllerBase));

    private string JsonPropertyName(IReadOnlyList<object> attributes, ModelMetadataIdentity key) =>
        attributes.OfType<JsonPropertyNameAttribute>().FirstOrDefault()?.Name
        ?? _jsonNamingPolicy?.ConvertName(key.Name);
}