Except that the PS5 is not doing well at the same time. 

No, the PS4 wasn't as "unpopular"; it was up against WiiU and 3DS, with the successful latter only about 3 years old when PS4 launched and the handheld had plenty of room to grow, with big games still to arrive.  So the PS4 had a fight on its hands and still managed its respective sales.  The Switch, on the other hand, is 7 years old now, has already played its biggest cards and the new system comes out in a year... and the PS5 still can't beat its sales for more than a week or two here or there - sometimes even when big games come out for it. 

And as others have pointed out, unlike PS4, some of those PS5 sales are not accurate for the region due to exporting.  What does it matter whether you can say the same thing about Switch?  Switch's sales numbers aren't a problem in that regard because, unlike PS5, sales are still great for its age and saturation point when factoring in exporting.

And sugarcoating the physical PS5 software sales with the "digital now being higher" argument only helps so much.  We're not just talking Switch beating PS5 on the top 30 physical charts, but dominating it.  That is bad no matter how you spin it for a console just coming off of its peak year up against one that it is being succeeded in a year, with years-old evergreens still outpacing much of PS5's new stuff weekly.

Do you really expect PS5 to be able to keep pace with PS4 aligned once Switch 2 arrives?  Now should be the time we see the bigger PS5 numbers because there is little chance that's going to happen next year in Japan.

The Switch is randomly up this week YoY for some reason so Japanese sales really are an anomaly at this point.

Your overall point is right but considering it has about a 600k lead over the PS4 and is increasing that lead every week it should stay ahead of the PS4 long term even if the lead gets smaller later on.

It may increase a bit more in the short term, but once Switch 2 hits the market I think the PS5's trajectory will change pretty drastically and could lose too much ground to keep up with PS4 going forward.

It's true that when you just look at the hardware comparison right now between PS4 and PS5 on paper it doesn't look that bad but when you look at the bigger picture, things change.  Basically, PS4 came out 3 years into 3DS' life and had to contend with the Switch 3 years later (with the WiiU as competition too, but... meh) and the console still managed 9.67m in the end.  Whereas the PS5 came out almost 4 years into Switch's life and won't have to contend with Switch 2 until over 4 years later, giving it more time with less competition.  So the PS5 should probably be more ahead than it is, especially when you consider the exporting.

We know the PS4 held up as well as it did in Japan once the Switch arrived, but I really don't think the PS5 will stand a chance against Switch 2.  We'll see though.

This is supposed to be the year PS5 takes over and profits from Switch not having much cards left to play...the chatter around Switch 2 really isn't slowing down the sales.
Glad they are taking their time to launch it. Games take so much time to make these days, i'd rather have a console launch 6-8 months later but have a killer first year than have a situation like PS5/Xbox where there is still troubles in the release calendar.

Switch has far more exports than PS5, it has been the case since its release in 2017. My first Switch was indeed Japanese. It's one of the reasons for Switch relatively weak ROW in comparison with Sony brand 

The case is even with higher exports in absolute numbers an humongous number of Switch units stays in Japan, probably not the case for Playstation 

Does it matter that they export Japanese sold consoles to somewhere else?

If it’s sold in Japan then it’s sold in Japan. They don’t double count.

Except that the PS5 is not doing well at the same time. 

No, the PS4 wasn't as "unpopular"; it was up against WiiU and 3DS, with the successful latter only about 3 years old when PS4 launched and the handheld had plenty of room to grow, with big games still to arrive.  So the PS4 had a fight on its hands and still managed its respective sales.  The Switch, on the other hand, is 7 years old now, has already played its biggest cards and the new system comes out in a year... and the PS5 still can't beat its sales for more than a week or two here or there - sometimes even when big games come out for it. 

And as others have pointed out, unlike PS4, some of those PS5 sales are not accurate for the region due to exporting.  What does it matter whether you can say the same thing about Switch?  Switch's sales numbers aren't a problem in that regard because, unlike PS5, sales are still great for its age and saturation point when factoring in exporting.

And sugarcoating the physical PS5 software sales with the "digital now being higher" argument only helps so much.  We're not just talking Switch beating PS5 on the top 30 physical charts, but dominating it.  That is bad no matter how you spin it for a console just coming off of its peak year up against one that it is being succeeded in a year, with years-old evergreens still outpacing much of PS5's new stuff weekly.

Do you really expect PS5 to be able to keep pace with PS4 aligned once Switch 2 arrives?  Now should be the time we see the bigger PS5 numbers because there is little chance that's going to happen next year in Japan.

Does it matter that they export Japanese sold consoles to somewhere else?