Additionally, although in Standard French /ɛ̃/ has migrated towards [æ̃], in Quebec French (and Canadian French in general) it is much closer to /ẽ/, reminiscent of Brazilian Portuguese em.
This divergence is well-documented: Standard (or what is called Northern Metropolitan French) has shifted its nasal vowels anti-clockwise / counter-clockwise round the vowel trapezoid, while Quebec French has shifted them clockwise.
The anti-clockwise nasal vowel chain shift in Northern Metropolitan French is still in progress (this paper states that at the turn of the century, it was "nowhere near complete"). Hansen (2001) showed that certain words were more susceptible to others, and that it 'started' with the merger of /œ̃/ and /ɛ̃/, leading to /ɛ̃/ moving anti-clockwise first. This then caused other ones to shift, but it seems speakers vary in how much.
According to this 2011 paper, Northern Metropolitan French has tended to maximise the nasality - (normal) oral vowel contrast by shifting anti-clockwise because "it enhances the perception of nasality". The Quebec strategy though employs more of an "epenthetic nasal consonant", adding it back.
The IPA was actually promulgated by the association called the IPA, or the Association phonétique internationale, established back in 1886 in Paris. The IPA in more or less its modern form was published two years later. The vowels /ɛ̃/ and /ɛ/ were certainly closer back then, and the notation used has simply stuck whilst the phonemes have slowly shifted apart. This issue does not only affect French nasal vowels; the pronunciation of Received Pronunciation in English has changed significantly since it was notated in 1917 in Daniel Jones's English Pronouncing Dictionary.