The notification is gone.
The notification reappears. I don't know if it's related to #14155 or #13458, but up until now notifications always went away after closing the app.

I also faced the same problem..... Actually it is not good idea to hide the download files in new update....
I can confirm the issue is reproducible on Firefox Preview Nightly 200908 (Build #2015762675)
Thanks for the report. This issue will be addressed on https://github.com/mozilla-mobile/android-components/issues/8354
This should be in the the 9/16 build.
Thanks for the update, I can confirm this is fixed in the latest nightly.
Verified as fixed on Firefox Preview Nightly 200917 (Build #2015764403).
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Thanks for the update, I can confirm this is fixed in the latest nightly.