If the data set exceeds a particular value, Google analytics shows sampled results on the dashboard. The limits beyond which data is sampled (>250k sessions, >50k rows, etc.) is given here: https://support.google.com/analytics/answer/1042498?hl=en&ref_topic=2601030
What about firebase analytics? Does it sample data in the same way for generating reports? Are the sampling limits same as those for google analytics given in the link above?