Using the Code search functionality on Bitbucket Cloud, there's a limitation of file size results.
Currently, according to our documentation: https://support.atlassian.com/bitbucket-cloud/docs/search-in-bitbucket-cloud/

We index files smaller than 320 KB – you won't see search results from larger files.

Hence, if you search for a file that has a size of more than 320 KB, it will not be shown on the search results.

Feature request:
It would be very essential and useful for customers to be able to search files with large sizes of more than 320 KB.

Workaround:
Search code locally using code editors