Bonjour Stéphane,

Thank you for pointing this out! The lesson has been updated to mention that both are correct, i.e. 'ai' can be pronounced [é] or [è] depending on regions (Paris area: [é] - Britanny [è]). Therefore words like 'lait / j'ai' will be pronounced differently depending on where you are from or with whom / where you have learnt French.

See links here: prononciation 'ai' [é]/[è]  -  pronounciation "j'ai"

I hope this is helpful.

Bonne journée !