Reproduces with SRP 7.1.7 in 2019.3. Does not reproduce in 2019.2 (SRP 6.9.2).
Reproduces in Version: 2020.1.0a18.2166 with SRP master commit 8823d0532c
Reproduces on Release/2019.3 branch of SRP, commit 4ebdde3ed6

Repro steps:
1. Use a project with Universal RP (do not have to have pipeline asset installed in graphics settings for bug to reproduce)
2. Download attached shadergraph and bring it into project
3. Open task manager to track the memory Unity is using
4. Open the shadergraph, note that the shadergraph's performance is good
5. Close and reopen the shadergraph 10 times
Expected result: no memory leak
Actual result: Unity is now taking up around a gig more memory