Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Distraction
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Diverted
Aircraft; Environment - Non Weather Related; Human Factors
During brief; maintenance write up for 'Cargo Door' caution had been reported with no prior pressurization issues and MEL issued. This was an additional threat to monitor for.  Upon departure; we received a 'cargo door' caution message; and noted the pressurization was indicating decreasing cabin pressure.  The QRH procedure was called for and ran.  Due to fluctuating pressurization indications; it was decided to divert to ZZZ1 for further investigation into the issue.In my opinion; this event was caused in part due to lack of recent currency as both pilots had been on COVID leave.  More important though was lack of threat and error management which led to rushing the QRH procedure.  This was a time threat and there was ample opportunity to slow down and evaluate the condition.  During the departure phase; there was some task saturation with multiple contacts with ATC and normal checklists procedures.In the future; I need to be more aware of my fellow crew member's task saturation condition level and be pro-active to verbalize when we need to make time and slow things down to avoid rushing through abnormal procedures.  Knowing the history of the maintenance issue; we should have completed the departure phase of the flight; requested to level off at 10;000 feet to reduce the workload; and run the QRH at that time.  Then; evaluate the condition and determine the best course of action.
During the departure briefing I mentioned to the First Officer that we needed to have the Cargo Door checked by ground personnel prior to departure per deferral and failed to do so.I have had this same deferral several times before and was overconfident with the knowledge that nothing has happened since the initial write up.  I have been out on COVID leave since December.  This was my 1st flight back online.  I did not sleep well the night before; I ate something that did not agree well with me for a late lunch the previous day.  I was borderline wanting to call in fatigued but thought how bad it would look after 30 hours at the hotel.Don't eat tainted food.  Get better rest.  Have some sort of reminder to make sure the deferral requirements are met before departure.
Air carrier flight crew reported not checking a cargo door that had a MEL on it due to a distraction before departing resulting in a divert.