I dare not say the authenticity of beef soup, but several shops in Huainan still know it.
On the 26th, you can see comments from Huainan netizens online. This is the most mentioned one. There are three high-rise buildings on the west side of Su Guo Science and Technology Building (the west side of Public Security Bureau).
There is one right opposite the power supply bureau, which is crowded every morning. There are very few people doing the same business nearby, because if you don't know this, I suggest you come in the morning and see which one has the most.
There is a beef seller in Dongcheng Market, which is in the northernmost part of Hongfu Supermarket. It is delicious.
There is a brother beef soup opposite Dongshan New Village, and it tastes good.
These are industry leaders in certain fields. It seems that if it tastes good, it should be authentic, but the taste of each family is different. I suggest a field trip to find something that suits the tastes of people in your place. Finally, I wish you success.