Has an NBA game ever ended 98-81?
It has. 98-81 has been a NBA final 35 times in 73,172 games. The first was Chicago Stags beat Baltimore Bullets on February 3, 1950; the latest was Oklahoma City Thunder beat Portland Trail Blazers on January 31, 2022.
That makes 98-81 the 678th most common final score out of 3,189 that have ever occurred in NBA. One point away, 99-81 has happened 34 times and 98-82 has happened 22 times. At one point the score disappeared for 31 years, between 1956 and 1987.