Be aware that BEN may move to being a Plus only stock. As far as I can see it doesn’t fit the description of what is supposed to be Basic stock (see Freetrade Plus for the definition of what is in Basic). That link tells you that the definition for UK stock largely depends on whether the stock is a FTSE350/AIM100 stock or not - and these indices of course change at least 4 times a year.
Shouldn’t be a surprise because Freetrade regularly reviews its Plus shares. You can see in the discussion that loads of shares recently became a part of the Basic Universe. Anyway, this does not affect Plus subscribers in any way.