Although Cixi hid the treasure well in the Forbidden City, didn't Eight-Nation Alliance think of looking for a part after she went in? Besides, after Cixi returned to Beijing, didn't she want to salvage it herself? Therefore, in my opinion, there are very few treasures in the Forbidden City, and there are even fewer existing gold and silver treasures.
Moreover, after the demise of the Qing Dynasty, warlords scuffled, and Puyi could continue to live in the palace, but there was no economic source. In order to maintain Puyi's life, the eunuchs in the palace must take valuables out of the palace and exchange cash for necessary daily necessities. Even the treasure in the well will be salvaged, which reduces the possibility of the treasure in the well again.
After the war, in order to protect the cultural relics of the Forbidden City, cultural relics institutions have transferred the cultural relics of the Forbidden City many times and in many ways. When sorting out the cultural relics of the Forbidden City, it is certain that there will be cultural relics in the deep wells of the Forbidden City. So at that time, the cultural relics in the Forbidden City well had been salvaged and collected, further narrowing the possibility that there were a lot of treasures in the well.
Even if there are treasures in the Forbidden City, the wellhead of the Forbidden City is too small, and people are likely to get stuck in the wellhead. If instruments are used, the space of the well is narrow and the construction is particularly difficult. Moreover, many wells are blocked by stones. If demolished, it is very likely to destroy these ancient wells and even lead to landslides, thus damaging cultural relics, which is not worth the candle. So, that's why no one went to salvage the treasure in the deep well of the Forbidden City.