Even though it is counterintuitive, the bench press is by far the lift that is the most influenced by fluctuations in body weight. Even if your muscle mass is the same, if you lose weight the bench will go down more than other lifts.
And that is true even if you only lose water... for example a few years back I was bench pressing twice a week. On tuesday I hit 425. Then on friday night I took a long hot tub with my wife and didn't have time to rehydrate. Woke up saturday feeling good and energetic, but couldn't hit more than 365 on the bench press!
And in the past, I noticed that my bench is directly related to my weight. At 200-205 I can hit 365-375, at 215-220 I can hit 395-405, at 225-230 I can hit 415-425 and at 235-240 I can hit 435-445. And that is true even if each individual muscle in the bench press (triceps, chest, delts) are just as strong at 205 then at 230.
My guess is that since in the bench the shoulder is doing a fairly dangerous action, the body protects itself when it loses some cushioning from the water retention or fat.
When you look at raw powerlifters, it is not rare to see a light man deadlift just as much as a big guy, but it is very rarely true for the bench.
Now, you regained some weight, but you might not have the same shoulder joint "cushioning" and as a result the body protects itself.
The fact that your other lifts are back tell me that you are not turning into a slow twitch bitch. The body is just protecting it's shoulders.