Because there is a lot of hot water in the bathroom, the scale in the hot water pipeline causes the blockage of the hot water pipeline, which leads to a large back pressure of waterway flow. To a certain extent, the water-gas linkage device of the water heater will think that the hot water faucet has been closed and the gas path has been closed. Without gas, of course it won't catch fire. If the hot water faucet is fully opened recently, the hot water pressure is low, which is more likely. Since the kitchen can catch fire, it is more certain.
It is recommended to clean and remove scale immediately. You can buy a set of disassembly-free descaling agent for gas water heater online, and use it to inject descaling agent into the water heater and clean the inside of the water heater and the hot water pipe. The operation is simple and convenient, and it can be cleaned regularly in the future, which can avoid the recurrence of this problem. Many people have used it, and it is true and effective.