They are very likely fine,
The most recent thing I can find is their stand from TACRA on August 1st for a one day event at the Berkeley Hotel Pratunam in Bangkok on the 11th floor, at stand C-24 selling furry art keychains.
Their stand on the TACRA site can be seen here.
Their last post on any social media was on their Facebook (Chestnutz Cnz) from July 31st talking about TACRA, and later posting their TACRA shop link in the comments on August 1 (9 weeks ago).
their twitter (@ChestnutGGEZ) is inactive, with the name still saying "馃敎Thaitails2026" which is a convention from March.
It's probably just burnout or one of their random disappearances for a little while.
Looking at their Facebook they seem to have also disappeared before from November 18th 2024, until March 19th 2026 when they said (roughly translated from Thai): "Can I make a sound for anyone who is waiting for me to come back to life? TwT".
Conclusion:
They will likely come back, even if it takes a while.
Though they might also just not want to make games anymore, and may only come back to other platforms, who knows.