Zeina stressing specific letters in some words!

Two weeks ago I used Zeina voice to generate the following sentence:
ثَلَاَثَةٌ وَعِشْرُوُنَ طِفْلاً مِنَ الصَّفِّ ا انْضَمُّوا إِلَى ثَلَاَثِيِنَ طِفْلاً مِنَ الصَّفِّ ب.‎
and everything went well.

Today when I generate Zeina voice for the same sentence I found obvious stress in the first letter in the words "طِفْلاً".

I am just mentioning an example but the issue exists in multiple words for sure.

Is there any update in the engines or so that caused that? and is there any possibility to use the old engine if so?

I the two audio samples for reference but I had an error when I tried to attach them to this message.

Thanks in advance.