Why does iOS Speak Selection read "2020" as "2020 inches" in English (UK)?

I've been using Settings > Accessibility > Spoken Content > Speak Selection to read some articles from various websites on my iOS 13.3.1 iPhone 8. Whenever it reads "2020" (without the quotes), it says "inches" afterwards. This seems to happen with all the UK English voices. I don't have any custom pronunciations configured, and changing the Speaking Rate doesn't affect it. As an experiment, I wrote the following in Notes. I've annotated it with what the screen reader says:

2019    // two thousand and nineteen
2020    // twenty twenty inches
2021    // two thousand and twenty one
1010    // one thousand and ten
2010    // two thousand and ten
1020    // one thousand and twenty
5050    // five thousand and fifty
202020  // two hundred and two thousand and twenty
20.20   // twenty dot twenty
20:20   // twenty twenty
"2020"  // twenty twenty
'2020'  // twenty twenty

I can't think of any cultural reason that 2020 without quotes would automatically mean inches, and only in the UK. Can anyone explain it?

Solution 1:

It's likely a bug, as I can't duplicate the behaviour in Notes on a Mac.

However, the reason for the confusion may be that ' and '' symbols are used as a shorthand for feet and inches (also for minutes and seconds in geographical co-ordinates).

Perhaps Notes thinks there is a double quote after the numbers?