EF core 5.0 doesn't detect change to DateTimeOffset's offset

I see the following bug with EF 5.0

var entity = dbCtx.Find<MyEntity>(123);//Load from DB context
entity.MyDateTimeOffset = entity.MyDateTimeOffset.ToOffset(entity.MyDateTimeOffset.Add(TimeSpan.FromHours(2)));//Switch the offset by 2 hours
ctx.Entry(order).State; //Return Unchanged but expecting Modified

I believe this happens because IEquatable<DateTimeOffset> considers that two DateTimeOffsets are equal if they represent the same absolute time. However, from a DB perspective, the code above should detect the change and persist the new offset in the column (which is of type datetimeoffset in Sql Azure)

[roji]

I can confirm this repros - and as @clement911 wrote this is due to the equality behavior .NET defines for DateTimeOffset, which doesn’t take timezone differences into account.

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@clement911 I’ve submitted a fix for this. In the meantime you can set up your own value comparer with the right behavior as described in the docs:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<Blog>().Property(b => b.DateTimeOffset)
        .Metadata
        .SetValueComparer(new ValueComparer<DateTimeOffset>(
            (dto1, dto2) => dto1 == dto2 && dto1.Offset == dto2.Offset,
            dto => dto.GetHashCode()));
}