You can control how the tables are printed using the df_print argument of learnr::tutorial(), which can be set in the YAML front matter of your tutorial:
---
output:
learnr::tutorial:
df_print: default
---
This sets the data frame printing method throughout the tutorial so that data frames are printed in the same way as a student would see the output in their own analyses. You could also set df_print: tibble to always use the printed tibble format.