You sometimes see this with real live humans who have lived in multiple counties.

Pay no attention to those fopheads from Kent. We speak proper British English here in Essex

Also very common with... most Canadians. We officially use an English closer to British English (Zed not zee, honour not honor) however geographically and culturally we're very close to the US.

At school you learn "X, Y, Zed". The toy you buy your toddler is made for the US and Canadian market and sings "X, Y, Zee" as does practically every show on TV. The dictionary says it's spelled "colour" but most of the books you read will spell it "color". Most people we communicate with are either from Canada or the US, so much of our personal communication is with US English.

But also there are a number of British shows that air here, so some particularly British phrases do sneak in to a lot of people's lexicon.

See a similar thing in the way we measure things.

We use celsius for temperature but most of our thermostats default to Fahrenheit and most cookbooks are primarily in imperial measures and units because they're from the US. The store sells everything in grams and kilograms, but most recipes are still in tablespoons/cups/etc.

Most things are sold in metric, but when you buy lumber it's sold in feet, and any construction site is going to be working primarily in feet and inches.

If anything I expect any AI-written content would be more consistent about this than I usually am.

See also how all (?) Brits pronounce Gen Z in the American way (ie zee, not zed).

Some people are not from usa or England.

Bullet points hell, a table that feels it came straight out of grok.