You Cannot Just Add Urea into a Formulation (Blog Post Version)

Yes, it has lovely properties and is very inexpensive. I have been doing a ton of research on how to formulate it. However, it is not stable in water. It decomposes in water to create ammonia. This is what gives Windex its classic smell. It has a high pH. So the pH increases over time. How fast this degrades depends on the concertation and temperature.

So what do we do? For people who have taken a chemistry class, the next idea would be to create a buffer. Buffers resist change in pH. From my research, creating a buffer is not easy to do. As all the things that we add have a pH. So, it make it a complex equation. 
Yes, there are ingredients that you can add to prevent this also, but unfortunately not available to home crafters. If you are a supplier and would like to know. Send me a DM.
Conclusion:
For home crafters, I do not recommend formulating with it.
For consumers, If your product with urea starts to smell like Windex, contact the company and discontinue use.
Sources:

1. http://www.thecosmeticchemist.com/molecule_of_the_week/urea.html

2. https://chemistscorner.com/cosmeticsciencetalk/discussion/10196/stability-of-urea-in-cosmetic-formulations

3. https://pubmed.ncbi.nlm.nih.gov/25043489/

4. https://www.reddit.com/r/DIYBeauty/comments/1033cjd/making_a_simple_5_urea_spray/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=2&utm_term=1

5. https://www.sigmaaldrich.com/US/en/technical-documents/protocol/protein-biology/protein-concentration-and-buffer-exchange/buffer-reference-center#citric2

6. http://www.iscd.it/files/UREA-FROM-THE-CHEMIST-S-POINT-OF-VIEW.pdf

7. https://chemistscorner.com/cosmeticsciencetalk/discussion/understanding-ph-buffers-ph-adjustments-in-skin-care-formulations/

8. https://chemistscorner.com/cosmeticsciencetalk/discussion/how-to-use-buffers-in-cosmetics/#latest

9. https://chemistscorner.com/cosmeticsciencetalk/discussion/stability-of-urea-in-cosmetic-formulations/

10. https://chemistscorner.com/cosmeticsciencetalk/discussion/urea/

11. https://www.formulationbio.com/products/buffering-agents.html#:~:text=Cosmetic%20buffers%20are%20substances%20that,mixture%20are%20in%20chemical%20equilibrium.

12. https://chemistscorner.com/cosmeticsciencetalk/discussion/understanding-ph-buffers-ph-adjustments-in-skin-care-formulations/

13. https://chemistscorner.com/?s=Urea&subset=topic&bp_search=1

14. https://chemistscorner.com/cosmeticsciencetalk/discussion/allantoin-and-urea-and-advantage-of-increasing-allantoin-if-any/

15. https://chemistscorner.com/cosmeticsciencetalk/discussion/urea/

16. https://chemistscorner.com/cosmeticsciencetalk/discussion/improving-ureas-stability-in-cream/