The flu is the flu. COVID-19 is COVID-19. Both are viruses - but they are different. COVID-19 didn't replace the flu. That would be like saying that this year the cold replaces the flu - and there is no flu, just colds. Nope - both exist. Independent of each other.

Now - could there have been some early confusion and some cases that were COVID-19 were attributed to being the flu? Sure - that's possible. But they are still different illnesses.