That is total nonsense. I use my DX340 at least 3-4 hours a day, with and without WiFi, with and without USB connected, with and without SD card, etc., and I have only found 1 minor issue in the latest firmware. Charging was fixed completely: all 3 chargers I have work without any issues. And no, I don't use UAPP (actually I do on my Z-Fold6), as I don't want Google stuff to be running in the background on a DAP. I feel sorry for those who ran into problems. But saying that it is full of bugs is just incorrect and not fair.
Btw I always do a full reset (via recovery menu) after any Android update. Curious to hear if those experiencing issues also did that.