First weekend sales in Japan:
Wii: 371,9K
Switch: 330.6K
PS4: 322.1K
WiiU: 308.6K
PS5: 118K (sold out, supply constrained)
PS3: 88.4K
360: 60K
XBO: 23.5K
XSX+XSS: 21K (sold out, supply constrained)
To be expected. Even if global launch shipment for Xbox and PS5 will be their biggest one ever, they now are releasing them in more countries, so several countries will get less units at launch. Specially the smaller ones for them, like Japan.
It's fair to assume they didn't have enough units to properly match the worldwide demand, and they prefered to send more units to their main marlets: USA for Xbox and Europe (specially the top ones: Germany, UK, France and Spain) for Sony.
I thought production was 10 or 15 million? Was that for the quarter?
Sony denied this Bloomberg info, they were fake news. Sony only mentioned they expect to sell this fiscal year more than PS4 did in the same launch period(~7M worldwide), never mentioned production numbers.
PS4 sold 1M in the first weekend in NA, and 4.2M worldwide during the first quarter.
But there is a difference between PS4 and PS5 launches: PS4 launched early in NA, while other regions like Europe, South America or Australia got it a coule of weeks later, and Japan had to wait until February, so they had time to produce more units for Japan.
This time, PS5 got released the first day on North America, Australia, New Zealand, Japan, Singapore, and South Korea. And a week after in the rest of the world. Which probably means that even if the global shipment for day one will be higher than with PS4 (sold out everywhere just with preorders), probably each contry received less units for their launch weekend, because this early shipment has to be spread between more countries.