Notification IF a cell is highlighted by 2 conditional formattings

Question

Is there a way to generate an alert or a notification WHEN a cell or some cells are highlighted by 2 or more different conditional formattings? Making that the upper conditional formating overwrite the lower one...

This notification should come after selecting a choice from the data validation dropdown menu in A15, F15, P15 and U15, in order to select another car avoiding a crash with the car before or after...

Attached the 2 cases:

• Case OK : each conditional formating highlghted diffrent cells:

• Case NOK : conditional formattings are sharing some cells:

To understand what I mean, here's the example I'm working on: https://docs.google.com/spreadsheets/d/1skYbRolzLWyxMe06Ppd5tLobksQ8gD9dHrBP3dwgZwA/edit?usp=sharing

Answer 1

Add another conditional format rule that combines the existing rules, but turns yellow, and move it to the top of the list of formats. For example, in F6:

=(regexmatch($F$15, "^Red") + regexmatch($A$15, "^Green") + regexmatch($A$15, "^Red")) > 1

Becuase those true values convert to an integer 1, there's a collision if the sum is greater than 1.