VMware Fusion 12.2.3
Kubuntu 21.04

1. Check for updates via Discover
2. install all update

Low Disk Space warning shown: Your Home folder is running out of disk space, you have 0 MiB remaining.

Ok great - we know what the problem is. Recover from a backup of the vm. Shut down vm. Open vm Settings > Hard Disk. Disk size is at 20GB. Increase to 40GB and click Apply: Virtual disk resized successfully. Use the disk maintenance tools in your guest operating system to resized or create partitions to fill the available space.

Well, a link to a KB article with some details would have been splendid. stackoverflow to the rescue: https://stackoverflow.com/questions/26471342/how-to-increase-hd-size-of-linux-running-on-vmware

Nice we are going back to vmware now: https://kb.vmware.com/s/article/1004071 "If you are running a file system other then ext3, you may need to research an alternative way of accomplishing this. Reiser has its own tool for accomplishing this, GParted Live CD is another popular tool for this."

Great, vm runs on ext4 - now what? Lets go with https://www.howtogeek.com/114503/how-to-resize-your-ubuntu-partitions/