Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Communication Breakdown; Distraction; Situational Awareness
ATC Issue All Types; Deviation - Altitude Overshoot; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Clearance
Environment - Non Weather Related; Human Factors
Controller had to have had a mask on as his communications were muffled and thus hard to understand.  We read back clearance to FL230 and as we were passing through 22;500 he said we were only cleared to FL220. He said to just continue to FL230 and that is what we did. No conflict was noted.
Air carrier Captain reported an altitude deviation during climbout and cited communication problems with a Center Controller due to the Controller possibly wearing a face mask.