One cause might be the reason Googlebot is at your site.

We're in the Mobile-first (re)Index update. This is an ongoing process where all sites are being recrawled and revaluated for this new index.

We also just went through a Core update, where some sites may have seen added activity from Googlebot.

Then there's the normal web spidering where Googlebot follows incoming links from other sites.

You may also see more crawls if your site is getting high traffic.

welcome to WebmasterWorld [webmasterworld.com], dheeraj3600!

if you analyze your server access logs for googlebot requests from a 20-30K day and compare it to a 4k day it may give you some clues.

Doesn't answer your question directly but it does the title of the topic...

if I update my theme, depending on the amount of changes, this will trigger 3-4x increase in traffic from Googlebot for a few days to a week.

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