Maybe I’m missing some nuances here, but I don’t understand why Dynadot is so ignorant about the matter.
Having worked with a lot of smaller registrars, this is an easy one. First, there is a desire to cover as many TLDs as possible. Some of that is because there are large portfolio holders you'd like to have as customers, and they may incidentally have a small number of domains in non-major TLDs. However, if they can't put their portfolio in one place, or most of it, then you are a less attractive registrar. At Uniregistry, we had one person pretty much tasked full time with dealing with onboarding TLDs. They would do what they needed to do from a business end, let the developers know the technical requirements, let me know if there was any impact on terms of service, I would update the terms, and the TLD would go live. There were something like three people doing full time customer support. Did they keep track of every requirement of every TLD? Nope. So, sometimes, the idiosyncracies of any particular TLD just wouldn't be apparent to them, and they might answer a support question based on what they knew about gTLDs, etc..
It's why, as a rule, when it comes to forum topics along the lines of "I have a problem with a domain name", then anything following "Their customer support told me..." can be random-generated text for all I care. And, applying AI to come up with wrong answers is not any better.
A lot of ccTLDs have eligibility requirements, and so, sure, there is a cottage industry of proxy registrants who can provide "local presence" or whatever it is the ccTLD registry requires. But at the end of the day if you are relying on somebody somewhere whose job is to collect payments for basically doing nothing, because you want to get around rules which were really just designed to prevent you from registering a name in the first place, then I wouldn't have high expectations on service levels. Part of the reason why they are collecting payments for doing nothing is that they are fully aware that they are doing it for people who wouldn't otherwise satisfy the rules.
Whois privacy is included by default, yet I was never informed who provides this service—let alone given the option to choose a specific provider.
I feel your pain, but at the end of the day AFNIC doesn't care what the registrar put in your cart.
Some of these proxies who get these kinds of deals with registrars are just awful. There was one that EuroDNS used to use for .eu domain names who would simply surrender any domain names against which a .eu ADR was filed, without bothering to check with his "client". Just crazy stuff.
So, just offhand, I don't know how "DEUP Service Inc." came to be the privacy service used for the domain names about which the OP is complaining, nor would I have any idea what some rando registrar puts in someone's cart when they register a domain name. How would I even keep track of that kind of information anyway?
But if that's how it came to be, then I can guarantee you the privacy/proxy provider was not selected by the registrar on the basis of the high quality or reputation of the service.
For even more entertainment, you can probably go back through many years of my posts here if you want my opinion on privacy services in general, and the zillion reasons why they are a bad idea. It costs peanuts to register and maintain a business entity if you want to protect the privacy of your personal data, and in the long run it saves a lot of heartache over people whose business model is predicated on their perception that most of their customers are probably crooks in the first place. And that perception is reflected in the sort of respect they have for providing quality services.