Date: 202011
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: Commercial Fixed Wing
Reporter organization: Government
Reporter function: Approach
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Situational Awareness; Human-Machine Interface
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Air Traffic Control; Person Air Traffic Control
When detected: In-flight
Contributing factors: Human Factors; Environment - Non Weather Related; Staffing
Primary problem: Human Factors

Narrative: I was working Position X with numerous runway restrictions. Due to taxiway and runway closures we were running 4-8 MIT (Mile in Trail) to our runways we utilize except for Runway XXL which was normal. Due to these restrictions; over feeding an arrival controller happens quickly unless you build space by vectoring and speed reductions. Although this is necessary almost every push now; you begin to get backed up and run out of airspace. ZZZ [TRACON] already does not have much airspace and when you vector almost an entire base leg that is entering the metroplex airspace it becomes congested rather quickly. I was utilizing Runway YYR for as many aircraft that I could from the ZZZ1 Center; Position Y sector. We have had issues getting our spacing from this sector so we have to start taking aircraft off of the arrivals and slow them to make it work. I had assigned Aircraft X; Runway XXC because he was too close to the proceeding aircraft to land Runway YYR. The Controller working Runway  XXC was already turning a 25 mile final so I vectored Aircraft X 130 [heading] down the Runway YYR final  descending to 5;000 to put them in the downwind. I was also feeding ZZZ2 downwind aircraft to Runway YYR if I had gaps. Aircraft Y was one of these aircraft and turned to a 310 descending to 060 for right downwind to Runway YYR. I kept working and noticed the CA on both aircraft and immediately intervened by climbing and turning away Aircraft X. Aircraft Y also got a descent to 4;000. Closest proximity was 500 FT and 1.7 miles. I was in my airspace the entire time but the controller working YYR was so busy that he did not see my aircraft descending to 5;000. Aircraft X was not in a good place to begin with. I usually stop these vectored aircraft at 7;000 so I assume the other Controller was just not expecting anyone there at 5;000. We have an incredible amount of traffic with very little staffing. We should certainly keep the staffing the way it is for COVID-19 for the safety of the facility personnel. The issue is the amount of concrete we have at ZZZ available to us. We are constantly doing things out of the norm that could potentially cause an error. I could have handled this better by stopping at 7;000 or 8;000.




Synopsis: TRACON Controller reported a loss of separation and cited traffic volume and staffing issues as contributing factors.