For students in the top two GPA deciles, there is no statistical impact between online vs. in-person education.
However, drop in performance becomes statistically significant (and increasingly dramatic) for lower-performing students, reaching up to a 0.7 point drop (on a 4.0 scale) for students in the lowest GPA decile.
This is measured by examining GPA the semester after taking an online or in-person course, in classes for which that course was a prerequisite.
In other words: online education = in-person education for great students, while it has a significant and negative correlation for average- and poor-performing students.
Bettinger, Eric P., et al. "Virtual Classrooms: How Online College Courses Affect Student Success." American Economic Review, American Economics Association, 2017, Vol. 107 (9), p. 2855-2875, pubs.aeaweb.org/doi/pdfplus/10.1257/aer.20151193.