SR22 pilot reported an RPM drop in the gauge display during cruise with no apparent loss of actual engine power or loss of airspeed. The pilot diverted and landed safely.

Narrative

At XA:42AM I departed ZZZ on a VFR flight plan in VMC conditions with a final destination of ZZZ1.Prior to take off I ran all of the standard checklists through the Perspective+ system on my Cirrus SR22 G6 non-turbo aircraft. I completed my run-up and noted that all systems were operating properly. ZZZ was still operating on CTAF as the Tower was not yet open; so I made my calls and departed to the southwest. Immediately after departure; I went over to Departure and requested a flight following to ZZZ1. I was given a squawk code and assigned a 180 heading. A few moments later; I was assigned a 190 heading. I performed a climb checklist on the Perspective system; and all systems functioned normally. The aircraft was set to full power and full mixture for the climb. At XB:47 AM; the airplane leveled off at 4500 ft MSL; I adjusted the throttle to 75% power and leaned out the mixture. I ran a cruise checklist at this time and noted that all systems were operating normally; and no anomalies were observed. At XB:52 AM; I ran a scan of the instruments and noted that the power was now showing 12% power; 2650 RPMs; and was drawing 16 gallons per hour of fuel and we were traveling at 143 knots IAS. No change in power or drop in thrust was felt; just the % power was showing far less than the aircraft was seemingly operating at. I pushed the throttle to full power and observed no increase in RPMs or change in airspeed. I immediately [advised ATC] and made a turn towards the ZZZ2 airport which was just off the right wing and back about 10 nautical miles from my location. ZZZ Approach immediately cleared me to land on Runway XX Right and then asked me to change over to Tower. I landed the airplane on Runway XX Right without incident and was met by the fire trucks. I was able to taxi and get the airplane to FBO.