it's not about the project, there is a leak of RAM.
Viewing post in Construct 3 3DObject Plugin comments
It helps most if you can provide a test project case, so I can see exactly how the addon is being used. For example, using a lot of instance model without using a template for them will cause GPU memory to grow.
For an example of prefab/template, see https://kindeyegames.itch.io/c3-3dobject-alpha/devlog/459808/example-prefab-project