The fourth quarter of the calendar year (October-December) or the Financial Year? (January-March)

Good question.

It be easier to follow universally if it was calendar year as different countries have different financial years

Calendar year

It means its gonna be delayed.

I want to think when they make a press release for the public, it means the final months of the year. When speaking to anyone involved with the company, executives, shareholders, and other employees, it must mean financial year, and maybe only sometimes.

Calander year. 10-12 that calendar year.

For context, I'm wondering about the recent Capcom leak which apparently has a new Resident Evil game for Switch scheduled for Q4 2021, wasn't sure if that meant end of this year or early next year.

Depends. Microsoft normally means fiscal year, for example, but most companies refer to the calendar year.

You can derive it from the context and the given company's history. It's either calendar year or financial year, the latter doesn't necessarily end with January to March. It's just that most companies use an April to March period to define their financial year. A different example is Microsoft whose financial years run from July to June.

Autumn. ie. the 4th quarter of the calendar year.