How to reproduce:
1. Open the user's attached project
2. In the Project browser, open the error SubGraph
3. In the Blackboard, add new Keyword/Enum property
4. Observe the error text (if it's correct, continue to step #5)
5. Delete the added Enum property

Expected result: error text: "Parse error: syntax error TOK_SHADER expected $end" and some Nodes still have errors
Actual result: error text is specific and there are no errors after deleting the added Enum property

Reproducible with: 8.3.1, 10.6.0 (2020.3.15f2), 11.0.0 (2021.1.17f1), 12.0.0 (2021.2.0b7)
Not reproducible with: 7.7.1 (2019.4.29f1), 8.2.0 (2020.3.15f2)

Notes:
1. With 8.3.1, 10.3.2 (2020.3.15f2), 11.0.0 (2021.1.17f1) error is correct when adding Keyword but after deleting it errors on some Nodes stay and are incorrect
2. With 10.4.0, 10.6.0 (2020.3.15f2), 12.0.0 (2021.2.0b7, 2022.1.0a5) error is incorrect when adding Keyword but after deleting it the errors disappear
3. Errors disappear after reopening the SubGraph window
4. Expected error text:
"Validation: Graph is generating too many variants. Either delete Keywords, reduce Keyword variants or increase the Shader Variant Limit in Preferences > Shader Graph."