For example, switching out the word ‘boot’ for ‘trunk’, or ditching the word ‘rubbish’ for ‘garbage’.
This is something I’ve noticed my 6 year old does pretty regularly. We went through a stage where ‘sweets’ became ‘candy’, ‘holiday’ became ‘vacation’ and ‘courgette’ became ‘zucchini’.
That last one didn’t happen but if you’re still reading you’ve got my respect, or as the Americans might say ‘…mad props’.
I’ve gone the opposite way - I’ve been replacing my American pronunciations with the British ones, like leverage starts with lee, like in lever, and that (software) patent starts with pat not pait.
I think it’s in response to my younger friends and colleagues sounding, to my ears, increasing American - they say gotten, zee, and on accident (things that are often more consistent, but just not cricket British). I’m old enough to remember the sound of dial up, so I probably wasn’t as exposed to US media growing up.