Changing wallpaper in Ubuntu Budgie causes memory leak

Running Ubuntu Budgie 18.04.3 with Variety 0.7.1 on a Pentium (dual-core) motherboard with 8GB RAM. Variety is installed via the official PPA from Peter Levi's site
I have had Variety changing the desktop wallpaper every 30 seconds, which has been causing the memory usage shown against budgie-wm (in htop) to steadily increase. Leaving the machine idle (my user logged in) for a few hours has caused this to take up all available RAM.
It can be cleared again by logging out (no reboot needed), but then the process starts again with the next log-in. I have changed the wallpaper-changing frequency to once every 12 hours, and now the memory leak has slowed right down.

I have seen exactly the same behaviour on a dual-Celeron laptop with 4GB RAM, with exactly the same versions of Ubuntu Budgie and Variety loaded from the same sources

In both cases, the images for Variety are only those in a local folder; it is not downloading any images from online sources.

The Budgie desktop team have tested changing the wallpaper frequently without using Variety, and have seen no memory leak.

I have been using Variety for a few years, and have only seen this change in behaviour within about the last two months. I have also seen it with the 4.x kernel as well as the 5.x kernel in Ubuntu 18.04 LTS. Unfortunately, I did not note which set of updates to my systems caused this change in Variety's behaviour