From an older paper which found that online courses involving pretests outperformed F2F instructions, but that online courses with no pretest showed no difference:

There exists a possibility that a pre-test works as a moderator affecting teaching and learning processes of ODE settings. For example, a pre-test might provide information for the online instructors to understand students’ academic ability to adjust the level of difficulty of the course content and offer appropriate feedback. Unlike F2FE settings where instructors gather information about student levels of understanding from facial expressions with direct communication, one of the biggest limitations of ODE was identified as a lack of information about students (Harasim, 2003). With regards to a self-learning perspective, a pre-test could help students recognize their own academic strengths and weaknesses. As Kozma (1994, p. 8) stated, “learning is an active, constructive, cognitive and social process by which the learner manages available cognitive, physical, and social resources to create new knowledge”, the self-recognition might work more positively in ODE settings in terms of individual and participatory learning.

There’s also, of course, a chance that a pretest in online instruction is a marker of a certain level/type of course design…