I guess IRCC would find little benefit from continuing the CEC&PNP draws after September, because while some inland applications definitely get finalized (PPR) within 3 months, most take longer than that. So instead of inviting new CECs which probably won't help meet 2021 target, they might/should really switch their focus and resources to finalizing all applications which are near the end while inviting FSWs to prepare for 2022 target. A great pool of "near the end" applications is FSWs from 2020 and 2021 most of which are passed except security. Security usually takes about 3 months, so IRCC could really quickly issue CoPRs then PPRs for FSWs and meet their 2021 goals this way.
The CEC&PNP preference was because there was no way to invite then finalize FSWs faster than CECs. But after September or October, the benefit of focusing on CEC will kind of fade and a better tactic may be to focus on finalizing any application, especially FSWs stuck at security. After September or October, I'm quite sure IRCC's perspective when sending invitations and prioritizing ongoing applications will be "can I finalize this application/invitation before 2021 ends?" Might be good for FSWs.