Originally I filed this bug as a crash after making a nodal connection using Shader Graph. Re-launching Unity and experimenting with the repro project failed to reproduce the crash. However the following operations result in temporary hangs ("spinning black ball of death" and inability to interact with the Editor) for roughly a minute per occurrence, using the repro project or another project. I am using a MacBook Pro, and all of the following operations used the built-in trackpad. I have not yet tried these with an external mouse, or on Windows.

- Option + Click + Drag to pan in Shader Graph
- Click + Drag to select multiple Shader Graph nodes
- Drag a connection between nodes
- Command + Z to un-do connection change
- Two-finger swipe up or down to zoom Shader Graph in or out

Even though I cannot consistently reproduce the original crash I set the Severity high because a long pause after most UI interactions in Shader Graph make it practically unusable.

Temporary hangs occur using:
- Unity 2021.0b7 (2021.1/staging 02180fe17a0e)
- URP 11.0.0

Cannot repro hangs using:
- Unity 2020.2.1f1 (2020.2/release 270dd8c3da1c)
- URP 10.2.2