Solved!! After all i just put the wrong type for the encoder here :
msgTrain = df[df.data_type=='train'].commentaire.astype(str).values.tolist()
msgVal = df[df.data_type=='val'].commentaire.astype(str).values.tolist()

It shouldn’t bee a list!!
I am not quite sure with wht is happening but … it worked!!
Thank you so much!
Peace!!