I am not sure I fully understand the problem, but the [CI SKIP] directive is ignored for promotions as of Drone version 2.1 (release July 2021). Here is the relevant commit that was responsible for the change in behavior: https://github.com/harness/drone/commit/e3f09c867dfbc3eaaa8fa64bdef41c092be11222
The [CI SKIP] directive is also ignored for tags:
https://github.com/harness/drone/blob/master/trigger/skip.go#L58
Perhaps the problem is not related to [CI SKIP] but something in your yaml? I recommend taking a look at this comprehensive thread that will walk you through all possible reasons a pipeline will not execute. If you are still unable to resolve, the last section of the thread includes a list of items that you can provide us if further analysis is required.