Let's not forget what happened in 2020: the world went into lockdown over COVID-19. Everyone was trying to do emergency gear-shift into remote work, and the demand for online collaboration services - and supporting infrastructure - exploded.

That IMO can easily account for majority of the increase since 2019, and it seems that this is another example of why you have to be suspicious of any average that includes pandemic years in its range. 2020-2022 was a unique period in all kinds of ways.

EDIT: Google's document even acknowledges that, in footnote 103 linked to from page 32. Quoting:

Although 2020 was the most recent emissions inventory available at the time the target was set, 2020 was deemed to not be representative of a typical year, because operations were impacted by the COVID-19 pandemic. The next most recent year with representative data, 2019, was selected as the base year.