Passed in 1992, the 27th Amendment prevents Congress from raising its pay during the same term . What is unusual about this amendment

The 27th Amendment to the Constitution was first proposed in 1789 by the 1st Congress to the state to be ratified. It was proposed with other 10 amendments to the Constitution but lacking the number of votes necessary, it did not pass like its others sister amendments to become what is today known as the Bill of Rights. It took about more than 200 years until 1992, after a campaign was started by University of Texas at Austin student Joe Watson in 1982. This amendment prohibited the increase or decrease of a congressman´s salary within a term in office. If there is to be a reduction or increment in the income perceived by a congress member, this must take effect only until the following terms office. (The answer is that it was first proposed more than 200 years before it was ratified).