Team guidance
This is a snippet of content strategy guidance I delivered to a UX writer surrounding the use of the word please in documentation.
I think your instincts are correct. I'd err on the side of consistency, especially when using words like "please," which gives an over-polite tone, and arguably an insecure one, to a set of (ideally) straightforward instructions that users are looking for to solve an issue. My stance around using "please" centers around the difficulty of the task, and this seems to be common in UX circles. If the easiest way to do the task is to call, users want to be told to call a specific number, the specificity would make me lean toward saying "please," because they had to visit this page to get this information. If they initiate a form accessible from a link that's easy to get to, that would be the easiest way to solve their problem, and assertive, instructional writing omits "please."
The user having to go through the flow of who they are and their needs on a contact form is pretty low effort for the user, and this seems common in tech products. I don't think our contact us form is any less intuitive than keeping the language generic—besides being personalized directly to that user when they open the form. Users just want to be told where to go to do the thing they need to do.