In game?  Or in benchmarks?  How are you keeping track of the core clock, OSD, GPUz log or something else?
 
The default 3D mode clock for the 3090 FTW3 Hybrid is 1800MHz.  It will boost to 1890-1950 depending on load and other things, stock, at least mine does.
Have you maxed out the power slider in Precision or Afterburner?  That probably won't change your core frequency much, but it also won't hurt anything to give it a try (these cards are extremely hard to actually damage through anything either of those programs will allow you to set, settings wise).
 
What PerfCap reasons are you seeing in GPUz if you're using that for monitoring?  If not, get GPUz, run some games or benchmarks & keep an eye on that sensor readout to see what it says.
 
What is your typical ambient temperature, 50C sounds pretty normal for these, mine runs between 42-55C depending on the load & the overclock or undervolt I'm running.
 
Your clocks staying down in the 1600-1800 range is definitely not normal, that's for sure.