We ran a high-loaded project and it is very important to monitor how the application utilizes cache.

I'd suggest to collecting the size of the cache values, something like Str::length(serialize($query['value'])). It can be configurable feature.
Also, I'd suggest adding the option for hiding cache values itself but show key names (disabling the collect_queries option disables listing of cache keys as well).

In our server infrastructure bandwidth between the app and Redis servers is the bottleneck, so monitoring cache value sizes during development is very important.

If maintainers are ok with this, I can send PR.