Like many have stated, it could be Thai incompetence or wrongful use.
Although this is quite an old article. It may still give us some useful insight
Thai's suggested that half of the stingray tanks they purchased developed "faults" very shortly after procurement. While the supplier claims it was misuse of equipment
Its absolutely a result of improper use.
The VT4 only carry 38 rounds of main gun ammo. Which is pretty standard for tanks as the Abrams only has 40 rounds of main gun ammo and the T90 has 43.
That’s the maximum sustained total rounds the gun barrels would have been designed for. For safety margins, they could probably do double that number in one sitting, but much more and you are basically playing Russian roulette with tank rounds.
The Thai army were using their tanks for non-stop area bombardment at max RoF in stationary dug-in positions, so they probably continuously feeding fresh rounds into the autoloader.
There are plenty of videos online of people doing meltdown tests with assault rifles of mag dumping none stop until the guns overhead and sometimes catch fire or suffer other catastrophic mechanical failure. That’s basically what happened here. The Thais kept pushing rounds through the barrel with no regard for safe operational limits or even basic common sense, in which case it was just a matter of time until the inevitable happened.
You can put any tank or even SPG in the world in that position and it would be exactly the same result.