many of those commits are in private repos.
I've seen people pushing e.g. weather data to GitHub in regular intervals blowing up their commit numbers.
Just check this to find crazy numbers: https://committers.top/
The days with lots of commits start rather abruptly at the end of 2023, so it being some sort of automation seems plausible.
Lots of organic explanations for that.
A lone developer can get away with infrequent commits at no practical cost. Maybe something happened in 2023 that made them a more prolific committer.