System

• Version: 0.31.0 (b617178ef491 2022-04-06 11:57 +0000)
• Platform: Ubuntu 22.04 LTS
• Firefox: 99.0.1 (snap Version: 99.0.1-1 Rev: 1232 Publisher: mozilla)
• Selenium: selenium-webdriver 4.1.1 (Javascript)

Stacktrace

Partial output from geckodriver; I think the command and arguments may be relevant:

26: 1651066926069	geckodriver	INFO	Listening on 127.0.0.1:39397
26: 1651066926080	mozrunner::runner	INFO	Running command: "/usr/bin/firefox" "--marionette" "-no-remote" "-profile" "/tmp/rust_mozprofileEmz3JC"

Firefox starts and shows this dialog:

Not sure what might be the cause or if this is really a geckodriver issue; not too familiar with snap either.
Maybe the geckodriver generated(?) profile in /tmp/ (see trace above) is not accessible via the snap packaged firefox binary(?)