Disk Usage Analyzer - Need help understanding result

[mahesh]

Hi,
Is there anyone here who can help me understand the disk analysis I just received, see screenshot below.

There are several things that puzzle me:

1/ at the top it says:

Error opening directory: 'tmp/snap-private-tmp': Permission denied

Why is permission denied?

2/

var, etc, and tmp were modified today, yet I was not at home today and just opened my computer minutes ago, while I was offline. So I could not have downloaded anything from the internet.
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