Seeing weird things here too. Dry and hot. Tomatoes look good, but peppers are small given all the heat we've had. Broccoli and cauliflower are normal size plants, but are way behind in production. Many of the cabbage are forming multiple misshapen heads.
Many types of stress can cause premature bolting. Just a few days of excessive heat may be enough. Extremely dry air is causing excessive wilting, even with adequate soil moisture. Plants just can't take up enough water to deal with the high rates of transpiration so they just shut down.
I don't know about the bok choy specifically, but many of the Asian vegetables are sensitive to day length. I don't plant any Chinese cabbage until late July or August as they will all bolt if spring planted.