Is Mandarin in China a dialect of Manchu in Qing Dynasty?

It should not be said that it is a dialect, but the result of Manchu's irregular learning of Central Plains Mandarin after entering the customs. Today, we can see that the pronunciation of Putonghua in Beijing is quite different from the dialects in traditional Central Plains areas such as Hebei and Henan nearby, but it is more similar to the dialects in Northeast China (just by listening to Zhao Benshan's cross talk), which shows that Putonghua has inherited the dialects in Northeast China to a great extent. At that time, all the nobles in the Qing Dynasty wanted to learn the Central Plains dialect, but just like people in other places learn Mandarin today, there will always be some substandard places, but the emperor said so. Who can say that the emperor is not sure? . . Therefore, the Mandarin of the Central Plains spoken by Manchu gradually formed a new phonetic system, which is today's Beijing dialect. Therefore, the current Putonghua can be traced back to more than 200 years ago, which is very different from earlier times, such as the pronunciation system in the Tang and Song Dynasties. So today, when we read Tang poems in Mandarin, we sometimes find that they don't rhyme, which is also the reason, because the pronunciation system we use has changed since the Qing Dynasty.

Ps: This is what I heard from my teacher when I was in a linguistics class (the professor came). It should be quite authoritative, but not necessarily. After all, academic things have their own reasons and are not absolutely correct.