### Vault is storing references to ephemeral sub-loggers leading to unbounded memory consumption

#### Affected versions

This memory consumption bug affects Vault Community and Enterprise versions:

- 1.13.7 - 1.13.9
- 1.14.3 - 1.14.5
- 1.15.0 - 1.15.1

This change that introduced this bug has been reverted as of 1.13.10, 1.14.6, and 1.15.2

#### Issue
Vault is unexpectedly storing references to ephemeral sub-loggers which prevents them from being cleaned up, leading to
unbound memory consumption for loggers. This came about from a change to address a previously known issue around
[sub-logger levels not being adjusted on reload](#sublogger-levels-unchanged-on-reload).
This impacts many areas of Vault, but primarily logins in Enterprise.

#### Workaround
There is no workaround.
