Keep in mind Lightening, when banks were starting to offer trackers, in my opinion, they copied existing contracts and put the word "tracker" at the start.
Most of the rest remained unchanged.
I think it's incorrect if Brendan is summarily dismissing contracts which contain the words "prevailing variable rate".
If a bank started a customer out on tracker, and gave customer option to fix, it is strange for the"fix" to act as some kind of trapdoor to move customer to SVR upon fixing /end of fix.
If that was the case it should have been described as "option to fix and lose your tracker".