Some notes from memory ...

Around the time of this transaction, Electrum users were being phished using the (previously) built-in server-to-client messaging function. The initial response to this was to remove the messaging function. Some users didn't upgrade, continued to suffer from the phishing problem, so there was a decision to configure Electrum servers to refuse to connect to clients older than 3.3.4, to force users to upgrade

TAILS does not update very frequently, so there was a period where the Electrum built-in to TAILS was unable to connect to servers. Also, the Python source of the post 3.3.4 versions required a later Python version than available in TAILS. A "binary" Electrum package (Appimage) was built and made available, and then (at least in Reddit) it was repeatedly promoted as "How to run Electrum 3.3.8 in TAILS", with instructions

Eventually, a later TAILS update had the necessary versions of Python and Electrum