Advice is certainly one of those uncountable nouns that's developing a renewed countable use in present-day English, along with researches, informations, and the like. What surprises people is to realise just how long-standing the countable usage is. In the case of advice, the OED has citations dating from the 15th century. ‘Getting good advices’ appears in one of William Caxton’s translations (1481). We are not talking downmarket usage here. The Duchess of Newcastle in 1664 talks about being ‘attentive to good advices’. And here’s Gibbon in 1796: ‘These are so many advices which it is easy to give, but difficult to follow.’
The examples continue right down to the present day, but the 18th century saw a shift away from the countable use when prescriptive writers took against it, preferring a partitive expression (such as piece of advice) - and also against other such nouns, such as information, which also had a long history of countable use (with citations from the 15th to the 18th century). Advices fell out of use in standard English, accordingly, but retained its identity in regional speech. The OED has some modern quotations, but they are all Caribbean and South Asian.
What seems to be happening is that the original instinct to use advice and the other words in both countable and uncountable ways is reasserting itself. People who have not been influenced by a prescriptive mindset in school are most likely to use it – which mainly means the millions learning English as a foreign language. Often the countable usage is reinforced by an analogous countability in a mother-tongue (as with informations in French). But it would be wrong to see the renewed plural use as solely an L2 phenomenon, as it is present in regional dialects, both national and (as the OED recognizes) international. I suspect it will become a standard usage again one day. In the case of informations there are signs of this already happening, in that the legal profession continues to use the plural form routinely in various special contexts. But advices isn’t standard yet, so in formal writing I would say stick with the partitive form for the time being.