Date: 202009
Local time of day: 1801-2400
Location: ZZZ.ARTCC, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Second aircraft: Light Transport; Low Wing; 2 Turbojet Eng
Reporter organization: Government
Reporter function: Enroute
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Workload; Communication Breakdown; Confusion; Distraction
Anomaly: ATC Issue All Types; Conflict Airborne Conflict
Detector: Automation Aircraft RA; Person Air Traffic Control
When detected: In-flight
Result: General None Reported / Taken
Contributing factors: Procedure; Human Factors; Airspace Structure
Primary problem: Human Factors

Narrative: I plugged in on Sector X after getting my weather briefing. The R side started the briefing as I was getting familiar with the position. Since traffic has dropped and picked back up from COVID my area often works in unusual configurations to manage traffic. I plugged into Sector X and noticed that I was going to working low altitude Y and two high altitude sectors X and Z. This meant I was going to be working the ground to FL370. I was listening to the briefing and scanning the board when I saw two aircraft flashing. The Controller had issued descend via the ZZZZZ3 to Aircraft Y at FL320 with clearance to 16;000 in our airspace and descend via the ZZZZZ1 to Aircraft X at FL340 converging together east of ZZZ3 VOR. I had not even gotten to the point of scanning the data blocks yet in the briefing because I would have mentioned this as appearing to be unsafe. Aircraft X started down as the two aircraft were converging (which started the flashing) and the R-side told Aircraft X to maintain FL330 when they were out of FL334. I worried that the aircraft wouldn't be able to stop their descent in time; but the pilot read back something like; 'Okay stopping at FL330.' The pilot didn't say they couldn't stop the descent and the Controller assumed that the pilot didn't need a traffic call because they would be able to level off in time. The R-side giving me the briefing said I thought these two procedures were separated. I told them that Aircraft X was direct ZZZZZ for the ZZZZZ3 which negates the prior restrictions and would make that a pilot's discretion descent to ZZZZZ. The aircraft came from Area [A] which is required to have the aircraft on full routing or APREQ the shortcut. Area [A] didn't APREQ the shortcut and the R-side didn't notice the abbreviated routing. Aircraft X descended to FL328 and told the controller that they got an RA. The R-side was finishing the briefing at this time and unplugged to I called traffic to Aircraft Y when they were approximately 1 NM past each other.Area [A] should leave aircraft on the appropriate routing or APREQ the shortcut. I see multiple times in each work day where aircraft are not on the right routing and I do not get a call to APREQ it. This is a recurring problem. Also; my area changes the configuration constantly throughout the shift to keep sectors from going 'red.' I appreciate that the Supervisor or CIC is trying to prevent a red sector but constantly changing configurations is confusing. Since March I have only worked this configuration (Y/X/Z) one other time and it is starting to seem like there is no consistency in the area. Lastly; the R-side should have read the routes of the two aircraft and not issued the descend via clearance to Aircraft X. Aircraft X started down earlier than expected but well within their ability and Aircraft Y stayed much higher than normal. Both aircraft did everything right. The two clearances are not separated when a shortcut is issued.




Synopsis: Center Controller reported that during a controller de-brief/switch an airborne conflict occurred due to the distraction.