As always, Bloomberg spreading fud and lies over Sony. They never considered to stop PS4 production in 2021, in the 'we believe in generations' interview Jimbo said that they were going to continue supporting during at least 2 or 3 years after PS5 release, and they always had a 10+ years cycle for their previous home consoles and the 10 year cycle would end in November of 2023.
They simply had to reduce PS4 productin during PS5 launch window campaign to make room to the record number of PS5s being shipped during its launch window, and since later the amount of total consoles they were able to produce was highly impacted by covid and chips shortages, and new PS5s shipments got sold out in minutes, they reduced even more PS4 production to make more room for PS5 production.
If it's real that they increased 1 million (all Bloomberg info about Sony must be considered as a rumor and a potential lie) then it would be because they increased the total production capacity but dont have enough chips for PS5, so went back to make PS4s, that since a bit before PS5 launch its shipments have been pretty limited.
Their sources indicated that production would stop by end of 2021 but plans have changed.
That Sony was planning for faster transitioning to PS5 this generation.
Bloomberg is lying again, they never planned to stop production by 2021. And Sony didn't plan for a faster transitioning, Jimbo said the opposite in the 'we believe in generations' interview: there's a huge active userbase, way higher than usual at this point (due to games as service or subs services like Netflix or PS Plus providing fresh content, plus a bigger amount of crossgen games due to multiple reasons like way more similar hardware and engines than usual, cheaper and easier porting, longer and more expensive production times that require extra revenue) so they planned to continue supporting PS4 for several years after PS5 launch because they knew that even if PS5 kept selling at record levels a big majority of their userbase would continue on PS4 for several years.