Changes in data collection since 2019?

[deepali-avast]

Hi,
I started to look at the trackers data and ran into some observations that made me wonder if there have been changes since 2019 to how this data is collected.

1. There seems to be missing data for 'has_blocking' in the trackers table from Jan2019 - May2019. Was there are change in instrumentation/user setup during this time? Is it ok to consider the remaining data during this period.
2. I noticed that the use of cookies (averaged over all trackers per month) is steadily decreasing from 2019 to 2021, which isn't intuitive to me. Has this been observed/understood? If there is any literature on this, could you please point me to it?
3. Is it possible to obtain the number of users or page loads from each country each month?
   thanks!