Is there a change monster def formula?

I notice a reduction on my damage on my bowmaster. Nothing has changed since the patch (I'm still wearing all the same equip and everything), but my overall damage has definitely went down by eye. So I'm just curious as to whether something else is introduced in this patch that not a lot of people are aware about, besides several glitches that are kind of annoying: summons don't work but still aggro, store remote controller doesn't work, vega scrolls giving an error code from time to time, and the list probably goes on.