After deploying the Symfony 7.1 upgrade for a client, we immediately noticed a high rate of cache misses for one of our heavily used controller actions. Digging through the changes for the relevant upstream packages, it looks like this was introduced by way of#52948 and changing the algorithm used for the default cache namespaces when anamespace attribute isn't configured on thecache.pool service tag.

To my knowledge, there is no way to configure a namespace for cache pools using theframework.cache configuration, so through the framework configuration, there is no way to avoid hitting this issue without either manually building cache services or getting creative with a compiler pass that runs before the coreCachePoolPass, so IMO it's best to call out the change in the upgrade guide.