8 GB of RAM is also on the low side for running our stack, especially when a feed update and vulnerability scans run in parallel, both of which can be very resource-intensive. See this post for further information. Is it possible to assign more RAM to the VM and see if the problem persists?
Since we also have multipe, if rare, reports of this problem still happening, I will open an internal issue to look into it. I cannot make any promises regarding a solution or a time frame however. If you want to support this process, please open a new issue at Issues · greenbone/gvmd · GitHub including full log outtakes, similar to the old issue GVM 20.08 crashes after disk (/tmp directory) runs full because of cpe xml split · Issue #1433 · greenbone/gvmd · GitHub.
Last but not least we recommend to update the whole stack to the current versions.