I'm assuming it's either an influx of players who only grind to the edge and then take a break returning for the new patches/prepping for Stormblood; or, it's that a lot of them are ready for it and have left until the expansion comes out so statics are breaking and you're seeing people who used to have regulars now having to deal with less experienced players and being grumpy about it. Throw that in with the fact that there's always a risk of getting a grumpy player in DF from time to time and it might feel like an increase in "toxicity".
I've learned to just not let those kinds of players get to me, along with not letting my limited amount of play time get me worked up if I'm having a bad run of wipes (PotD recently, for instance). Some days I just "stay home" on Sargatanas and work on leveling one of my gather/craft classes up a little.