Short answer: Nothing to worry about regarding the port 6668, mostly.
The bulb you have is really common, sold under multiple brand names, and the IoT implementation can be found in plugs and switches, as well.
The bulb you have has an ESP8266 inside. It's controllable via a library called ESP8266MOD, I think. But I've always seen it referred to as Tuya, and the tuyapi, or python-brihome provide implementations that work using the UDP interface the device provides.
I happened upon your question looking for information on the Cree Connected Max bulb, which is definitely the same bulb. These bulbs are equipped with both WiFi and Bluetooth. The Bluetooth, I think, can be used for control of the bulb in general, but with mine, it was only used as a convenient way to talk to the bulb for the purpose of configuring WiFi security.
As for the mostly part...
I haven't taken the Cree protocol apart like I did the Ankuoo, but I poked at it a little bit this weekend. The biggest concern I had on the Ankuoo device, I think (5 years ago) was that when you sent the command querying bulb state/info, there was a large part of that packet which appeared to be encrypted. And, I think, the packet actually contained my SSID. There's just no good reason for them to send that out, and since I was able to perform every function of the app, and read every value the app displayed (along with several others), I didn't trust that data.
The good news is if you're concerned about the security of the device, you don't necessarily have to toss it.
My solution was to treat it as untrusted: I isolated my bulbs; they cannot talk outside of the subnet they are on which is reserved for IoT; my Home Assistant server can reach it, but it can't be seen from the subnet. I also created a separate SSID for it, with its own shared key. I allow broadcast from the bulb and traffic to the bulb. This makes all of the cloud features fail, but I configured Home Assistant to manage the bulb and simply control it through UDP broadcast.
And frankly, the user experience ends up being better this way. When I issue a command to the bulb, the UDP broadcast is picked up instantly. There's no round-trip to a Chinese[0] Command/Control server.
If the small company behind the product goes out of business, the bulbs are still controllable -- as far as they know, the company is out of business. [0] That sounds derogatory, but was simply meant as fact. With the cloud services enabled, my Cree and Ankuoo devices communicate exclusively with servers hosted in China, but I wouldn't care if they were hosted in the US.
