I recently switched to the GMail redesign where Google Sans is used for the subject text when displaying emails.
I noticed that where a lower case 'r' is followed by a 't' - as in 'Start' - the 'r' is taller than the 'a' before it. However where it is followed by an 'a' - as in 'preparations' - the two letters are the same height.
When trying to select the word with the mouse, the 'r' and 't' could not be selected separately, so presumably there is a ligature. Why would the size of the 'r' increase next to a 't' but not other letters?