Octopus seem to intentionally obfuscate the T&C's for tracker cap, from the
ms thread
"Once you've signed up to the tariff, the cap will be in place for the length of your tariff (12 months) - but as with all of our tariffs, we're constantly reviewing wholesale energy prices and may amend the cap in line with the cost of energy down the line."
"The cap that's active when you sign up will be in place for the length of your tariff. Tracker exposes you to wholesale prices, astronomical at the moment, so we’ve included a cap to protect you from market fluctuations, but it could be different if you signed up at a later date"
from earlier discussion here they haven't changed it so far on existing contracts, but could do so with 30days notice .. coincidentally we are 30 days out from new ofgen cap start