System.InvalidOperationException: 'OnConfiguring' cannot be used to modify DbContextOptions when DbContext pooling is enabled.

报错原因因为你在依赖注入使用的是连接池AddDbContextPool，则不能在OnConfiguring配置参数 需要在AddDbContextPool中完成配置

builder.Services.AddDbContextPool<MyDbContext>(options =>
{
    options.UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking);
    options.UseSqlServer("xxxx");
});