Hard for an apples to apples comparison due to how they organize data. The best I could find for apples to apples was ages 0-49.
For ages 0-49 there was an estimated 23 Million Symptomatic Flu Cases, there was 8,500 deaths (Data from 18-19, CDC).
For ages 0-49 there has been 4 million COVID Cases, there has been 8,100 deaths (Data from CDC).
Here is where it gets tricky. There was an estimated 41+ Million Flu cases for that age group in 18-19 (CDC), I have seen estimates that the true COVID case number is 5x higher, I've seen estimates that it's 10x higher. If its 10x higher, then mortality rate would be the same as the 18-19 flu. If its 5x higher, then COVID would be twice as deadly for people under 50 as the flu.
So people who are saying it's for sure less deadly, would have to know the true case number, which even top scientists from MIT are still trying to figure out.