If I had to guess, you have probably lost some muscle weight along with a fair bit of water weight. It happens. By the end of next month you will know for sure. I won’t be at all surprised if you gain half of it back...or more.
Still, if weight loss is a goal, then build on it and turn it into a positive beginning!
The muscle loss is the bad part. Finally broke 200(198) But I can see an older mans bicep, the skin being "not as tight." 39 pounds leaving your frame will do it.