I get this in my App store app when going to the updates tab.

[BelgianBoy]

Have I been hacked or is it malware? That's not the normal look of this page.

 

[BelgianBoy]

When I try to update it downloads but after restart nothing happens...

 

[Brian33]

I have the same messed up display when I open Mac App Store. I do not think it is malware, but I don't have an explanation. I'm running High Sierra on an old (Early 2011) Macbook Pro. I do not have the same problem on my iMac running Mojave.

It looks totally wrong but I'm still able to update apps.

 

[glenthompson]

I have the same problem on my old iMac running High Sierra. Air running Catalina displays just fine. May be n artifact of lack of updates to the old OS.

 

[Ritsuka]

It's just a server side issue. Someone at Apple changed something and didn't test it on older macOS releases.

 

[BelgianBoy]

I tried the updates again and it finally worked. Heard from others too it was an iCloud problem at Apple.