Belgian here, my wife is French Basque from Baiona. Her grandmother says she can't understand the Spanish Basques anymore. She says they created a new language or some hybrid form intended as a unified dialect or something. Has there been a spanification in recent years?
Labort dialect = easy-medium mode to understand Batua.
Also, if a Batua speaker it's used to speak the Western subdialect (Biscaian) and unadvertedly introduce "jargon" into Batua, it would be difficult because that dialect has lots of Latin/Castillians borrowings.
Spanish has similar issues too. Pick up a Chilean/Argentinian "chav" and partner it with a Murcian teen guy. If they mainly speak in their subdialects, either guys will have a hard time, even if both speak Spanish.
OFC if they keep a conversation on "semi-standard" Spanish they'll understand the 99%, 100% if both are speaking about academic terms or just a random serious article/news in a newspaper/web site.
Still, the RAE dictionary in Spain is huge, it covers ALL the manerism/idioms/jargon of Spanish all over the world, so any speaker from Mexico to the Patagonia or Iberia can easily query the online RAE dictionary for local terms such as molar, rentar, pasada, chévere, chido, tío (not in familiar terms), bacán and so on.
I wasn't aware that this is the perspective from the French side, but I can easily believe it.
There are a few factors.
Generally the Spanish basque provinces have a significantly larger population, larger economy and more autonomy than the French provinces. In France Basque is not an official language in the region and is only available with private schooling. France is also very Paris-centric and very little support is given to the fringes. In Spain we keep the vast majority of our taxes, have our own local parliament and president, as well as fully independent social security, healthcare, police and education, almost all in basque, public and private.
As a result, the vast majority of support for Basque has been focused on the Spanish regions, which might have increased the separation. There is indeed a Standard Basque defined during the 60s for education, media and governance. Not sure if she is referring to this, it did consider all seven major dialects, including the French ones, but it is quite biased to the dialect from the central province (Gipuzkoa) and is significantly different to dialects at the edges of the region, to the point where mutual comprehension is a legitimate challenge.
The French dialects also have, well, a strong French accent, including different vowels, I also struggle to understand them. Whereas the Spanish dialects have almost the exact same phonemes as Spanish. It would probably sound like Spanish to a non-speaker, even if the grammatical differences are vast.
It is also possible that she is referring to the fact that many people in the Spanish provinces just don't speak Basque very well. This is actually because of a positive achievement: most students study in basque now. The thing is that often their parents don't speak it, they tend to become friends with others with Spanish speaking families, and they end up just using Basque for school. And in school they learn to understand the language and write it well, but struggle to speak it, often with a heavy dose of Spanish elements and sentence patterns.
None of this is all that new though, unless by "recent years" she means the last 30, which is not unreasonable.
Not to say that any of this is funny in any way, but I've always found it fascinating how mankind can find humor in even the worst facts of life. It might not always be pretty, but in this case there is a beautiful and IMHO hilarious movie about the subject of facial mutilation in the first world war period: Au Revoir Là Haut, translated as See You Up There in English.
you really have to read "going postal" to fully get it. the book works well as a standalone even if you haven't read any of the other discworld novels, and is excellent.
