revision kit

No - it expired in June. Please see this post https://opentuition.com/topic/changes-from-june-2020-to-september-2020-acca-exams

I have watched all the updated videos and read the updated AAA notes for December 2020 exam. However I am asking about the revision kit. In your post it says there is a small change to the syllabus. But there isn't any changes to the revision kit right? I just tried comparing the updated BPP kit (soft copy) with the older kit (hard copy). There is no changes.

Then you have answered the question yourself. I wrote in the update notes pdf: "Great care should be taken when referring to past exam answers which have not been updated. Any references to concepts of broader safeguards (“created by the profession”, “in the work environment”, “implemented by the entity”) should be disregarded as safeguards, as they do not meet the definition (above)." I would be surprised if this is not relevant to the BPP kit because I would expect it to include some past Q which deals with safeguards. If however the BPP kit does not include this topic my advice is redundant in respect of the kit. (I do not have copies of kits.)

What must be used instead of using the concepts of broader safeguards with respect to the new update?

If you download our AAA notes and search "safeguards" you'll find it in the ethics chapter.