Memory limits for Tor process


I’m running Tor with MaxMemInQueues 1 GB for many years.
But today I noticed that Tor process uses 2 GiB of RAM.
What kind of data Tor may store, which is not limited by MaxMemInQueues?
Is it related to latest attacks?
I guess that increase in consumed memory could have happened today at 01:00 UTC, but I’m not sure, I’m not monitoring it directly.

From this topic: [tor-relays] relay memory leak?

Selection of 75% of total memory is a strange decision.
Tor easily exceeds 1.33 (1 / 0.75) of MaxMemInQueues.
My record is 3.5 GiB working set with MaxMemInQueues 1 GB.
For selecting of the best value for MaxMemInQueues it is better to know at least approximate formula for maximum total memory consumption of Tor process.

With version maximum working set was somewhere near 4.5 GiB.
Then was released and for ~month maximum RAM usage was around 1.6 GiB.
Last week RAM usage started to crawl up and today it is 4.4 GiB again.
Do we need to solve this problem?