Regardless of font, the following piece Knits to italics on the eta value. Below is complete markdown code that will reproduce the issue
The tutorial group (M = 9.0, SD = 1.0) scored highest, followed by the lecture (M = 7.0, SD = 1.5) and discussion groups (M = 4.8, SD = 0.8), F(2, 12) = 15.8, p < .001, \eta^{2} = .72.