bug#67690: Bug in command sort?

[Oleg Moiseichuk]

Hello!

I've got a list of IP addresses, each of them is prepended by its frequency 
counter (please find attached in the file list-1.txt). I need to sort them from 
most frequent to least. I tried using this command:
sort -t '.' -n -k 1.1,1.8r -k 1.9 -k 2,2 -k 3,3 -k 4,4 list-1.txt
But I've got some weird results.

Ok, I merged these counters with IP addresses using awk (file list-2.txt). Now 
they use the same separator and I can simplify the command:
sort -t '.' -n -k 1,1r -k 2,2 -k 3,3 -k 4,4 -k 5,5 list-2.txt > sorted-a.txt
It looks like as sorted properly but some entries with the counters 13 and 10 
are misplaced.
Strangely enough, when I use direct order, they are sorted correctly:
sort -t '.' -n -k 1,1 -k 2,2 -k 3,3 -k 4,4 -k 5,5 list-2.txt > sorted-b.txt

Is it a bug or I'm doing something wrong?
I checked this in Ubuntu 22.04, sort version is 8.32.

--
Best regards,
Oleg Moiseichuk

list-1.txt
Description: Text document

list-2.txt
Description: Text document

sorted-a.txt
Description: Text document

sorted-b.txt
Description: Text document