It should be a modern imitation for the following reasons:
1. The paper has obvious signs of wear and tear. In layman's terms, writing paper is modern paper, not paper made in the old days.
2. The framing does not conform to the ancient form and is similar to modern machine framing.
3. The most important thing is that the writing is weak and superficial, which is definitely not Liu's style.
4. The seal does not conform to the seal management and seal system of the Qianlong Dynasty. The so-called "imperial gift" seal is not included in the Qianlong seal book.
5. Liu Yong's seal belongs to the "Chen" style, which is inconsistent with the system. The Liu family used the "Shi'an" Zhu Wenfang seal.
6. The ink pad used has serious oil smearing, which is a characteristic of modern ink.
It took some effort to write this, so it has some collection value. You should see more authentic works to know the truth.
The number of Liu Yong's authentic works in existence is still considerable, and there will be authentic works circulating in the market. The museum mainly has collections in the north. His calligraphy is very skillful.