@Tachikawa first time seeing this? It's a great way to make a tea. Im russian, and I dont know anyone, who uses it for coffee, but for tea - it's the real deal, everyone buy it for tea and tea only
Acidic foods can soften tooth enamel, making it weaker. You wait for a bit in order to allow the enamel to reharden and get strong again so your toothbrush doesn’t hurt it.
Food creates acid inside mouth and the acid level is high during meal.
This acid can wear off the tooth enamel.
So brushing teeth right after meal means attacking the tooth when it's weaken, so.. more enamel worn off.
More enamel wear off, more frail the tooth.
Saliva is the body natural way to cleanse the teeth, but it need time.
So usually it's recommended to just rinsing mouth with water right after meal
and brush teeth at least an hour after meal.