Expressions in property values are not expanded anymore

In our logging submodule we are using log4j2 properties with value expressions to do things, e. g.

<Property name="thing:Environment" value="${env:ENVIRONMENT}" />
<Property name="thing:Instance" value="${env:HOSTNAME}" />

However, since we upgraded to 2.17.2, the expressions are not (always) expanded anymore, i. e. the log will contain environment:${env:ENVIRONMENT} rather than environment:my-fancy-env.

The behavior is reproducible, however different applications behave differently, i. e. the same configuration yields different results (as in a race condition). The behavior is the same for the same config and application.

Our current workaround is to downgrade to 2.17.1 for the time being.

Is there maybe a connection to recently introduced raw values? Is this related to LOG4J2-3434?