So, are you saying that there is a bus and tram discount which can be loaded on a normal adult Oyster card, which is different to the bus and tram discount photocard? The photocard certainly seems to have a weekly cap according to https://tfl.gov.uk/fares/find-fares/bus-and-tram-fares.
It’s the discount that is applied to a normal Oyster card when you have the photocard
The link to the fares mentions the price for a weekly bus/tram ticket at £12.30 but if you use it as PAYG from Monday to Sunday then it doesn’t cap at £12.30 – I myself have spent £12.70 from Monday to today half expecting my last fare today on the 428 to be 45p but instead charged the normal 85p.
I haven’t used any other modes of transport to muddy the waters and potentially confuse the system.
I notice on the normal fares where it caps at £5.25 a day that it does have a specific column for the weekly Monday to Sunday cap which matches that of the price of a weekly pass but this column isn’t there for the discounted rate.