When you go to Bitcoin Core source readme file (
https://github.com/bitcoin/bitcoin )
You will see very early line
What is Bitcoin? Bitcoin is an experimental digital currency that enables instant payments to anyone,
In my opinion, whole word is an experimental.
In that sense, I do not see why
BTCitcoin would need to state itself as an experimental.
It is more than 10 years old. I would just say it is in active development.