yes, its probably waiting to complete rockstar social club

Press STEAM button and check if there is not another window under RDR2

Rockstar launcher waiting on the background. Goto desktop mode to sign-in.

For rdr2 and mass effect i found it was better to go into desktop mode and then launch the game that way for the first time so you can login to all that extra crap. Once you start the game fully then go back to the normal steam os

Did that on gtav for me, launched on desktop mode, logged in then ran perfect on gaming mode