FWIW:
User report:[1]
https://blog.torproject.org/comment/277375#comment-277375
Sanitize the add-on blocklist update URL
https://trac.torproject.org/projects/tor/ticket/16931
related, old, closed ticket (unresolved):
TBB-Firefox sends OS+kernel in update queries to Mozilla
https://trac.torproject.org/projects/tor/ticket/6734
[1]: "TBB-Firefox sends Linux kernel version in extensions blocklist update queries to Mozilla. 6 years old ticket closed
https://trac.torproject.org/projects/tor/ticket/6734 without fix this privacy issue.
>From Ubuntu 18.04.1 LiveCD
/v1/blocklist/3/%7Bec8030f7-c20a-464f-9b0e-13a3a9e97384%7D/60.2.0/Firefox/20180204030101/Linux_x86_64-gcc3/en-US/release/Linux 4.15.0-29-generic (GTK 3.22.30 libpulse 11.1.0)/default/default/1/1/new/
about:config
extensions.blocklist.url:
https://blocklists.settings.services.mozilla.com/v1/blocklist/3/%APP_ID
Also it send TOTAL_PING_COUNT to tell mozilla how many days you use TBB."
