Upgrading GIT to 2.16.2 will allow 2 advantages (there are others - see release notes):

1. Uploading or fetching a large # of tags in a commit is substantially quicker.
2. 2.x and later support the --shallow-since CLONE option:

#!python

$ git clone https://my-repo --shallow-since="2016-10-01"
Cloning into 'myrepo'...
fatal: Server does not support --shallow-since
fatal: The remote end hung up unexpectedly

Git release notes for 2.16:
https://github.com/git/git/blob/master/Documentation/RelNotes/2.16.0.txt\\
https://github.com/git/git/blob/master/Documentation/RelNotes/2.16.1.txt\\
https://github.com/git/git/blob/v2.16.2/Documentation/RelNotes/2.16.2.txt

Update: Thu 08, Aug 2024

Bitbucket has embarked on frequent incremental upgrade to fundamental technologies used for hosting git repositories. We are using the latest version (or a version very close to the latest) of git. At the time of updating this ticket, we are using git 2.45.2 version and updating to newer versions at a regular cadence after internal testing and via progressive rollout.
 $ curl https://bitbucket.org/site/info | jq ".system.git"
"2.45.2"