The presentation is "nice", but not even close to what it needs to be for making any assumptions on the result. Questions that are necessary to be clarified:
1) What is your source? - the slides only state it's the biggest platform.
2) How do you compensate, that your dataset only represents x% of the real offers?
3) If you think you have a reasonable share of the job offers, how do you justify this assumption?
These are the main questions, that I would ask if you tell me to use it as business information - all the technical stuff is secondary. But there are more:
4) How do you compensate a change in recruitment strategy? You are just looking at one platform.
5) What makes you sure, that every item in your dataset is interpreted correctly? Can you somehow make sure, that your parsing and reformating is always correct? Can you verify that? Can you detect if not?
6) Can you detect a change on the website itself, e.g. new categories, differences in job description?
Also my experience is different, with getting a ton of job offers currently, directly via business network, I'm willing to look at a statistics based bigger picture that changes my mind. But the interpretation and the harsh change, together with these open questions make me believe that you more likely have a technical problem. So my advise would be, spend a lot more slides on the data and not the acquisition, because all acquisition effort is useless if you can not verify your data and results.
