Considering the original reported issue, where memory grows to very high levels 25G) after shorter duration, disable pruning seemed to have contributed to a significant improvement. Considering customers will be upgrading from 6.6 and/or initial evaluation of 7.x would get a much better resource consumption experience relative to 6.6, where we had very high memory consumption due to stats.
This is not to say that we are satisfied with the current state. We'll continue to dig in and eliminate Prometheus continual memory growth to ensure it is capped. At this point the issue is clearly identified and acknowledged by Prometheus engineering. They have been working on the issue and provided a few patches, but have not merged them. We have experimented with these patches and determined they are still insufficient.
Given above status, and per maintenance meeting, we recommend not to introduce any delay for releasing 7.0.1 and release as scheduled (1st week of Sep).