Dev and testing happens in multiple iterations ideally what call it now agile - when PI are programmed to happen across life cycle of product.
you are in a new project as project test owner - how you deal with a very old evolving brain dump of requirements being given by pm and implemented by dev then delivered by project test owners.
how you deal to show high efficiency even in lack of documentation and entities required to deep learn about past tech, dev, tests.
You can be a source of friction in the correct places I guess, by asking for example for recorded demos as video clips for training new team members - think of it as documentation. That will suddenly make the requirements presentation meeting a lot more focused and force the program owner or project owner to not waffle.
Or just make loads of notes, but ultimately the project test owner is probably not talking to the project owner at least once a day is my guess. So those notes on all the brain-dump changes from the team-leads or from the developers themselves, are going to be pretty sparse anyway. This is why many QA teams gradually drift towards functional testing only, and leave usability and security to members in other roles?