On the same tweet that reported that the Switch outsold all the other consoles combined last year in the UK, Christopher Dring said:

"More PS5s and Xbox Series consoles were sold compared to PS4s and Xbox Ones over the same period when they launched. It's pretty impressive."

In the same conversation, another user asks: "PS4 and Xbox one sold slightly less than 900,000 in 2013 , can you tell us if PS5 and XBS combined did less or more than 1 million?" to which he answered, "Oh they didn’t quite get a million. GSD and GfK have slightly different figures so it’s not quite that clear cut."

Source:

To be expected Id say.
It was known PS5 would have more units available than PS4 in 2013 which is most likely the difference maker.

I'm not really surprised about the PS5, but seeing as the XBS has been constantly out of stock over there, I was starting to think that maybe MS had not been able to ship enough units.

There are no sales numbers that mean anything yet. Everything has been sold out, just like everything was sold out at the beginning of the last generation. We don't get any valuable information until supply catches up to demand. Then we'll be able to gauge the actual demand for these systems.

Nintendo really won 2020 with minimal effort despite what was happening around the world.