Diagnosis
This is almost always carbon fines or air from the new filters contaminating the water. New carbon block filters need to be flushed thoroughly.
How to Fix It
You need to flush the system. With the storage tank valve closed and the RO faucet open, let the system run for a good 30-45 minutes, sending all the new water straight down the drain. This purges the carbon dust and trapped air. After flushing, close the faucet, open the tank valve, let the tank refill, and then drain that first full tank as well. Taste should be back to normal after the second tank.
If That Didn't Work
Verify you installed the filters in the correct order. The sediment filter goes in the first housing, the carbon block in the second. If you swapped them, carbon fines could be getting to the membrane and causing taste issues.
Heads Up
Always use a wrench to tighten the filter housings, but don't over-tighten. Hand-tight plus a quarter-turn with the wrench is enough. A loose housing can also let in unfiltered water and cause bad taste.