Let us see what they have to say regarding this issue

Ibn Hajar quotes Ibn Bataal, who said

قال ابن بطال : روى أهل مكة واليمن عن ابن عباس إباحة المتعة ، وروي عنه الرجوع بأسانيد ضعيفة وإجازة المتعة عنه أصح ، وهو مذهب الشيعة

Ibn Bataal said: it is narrated by people of Mecca and Yemen from Ibn Abbas regarding permissibility of Muta’a. And narrations regarding his change of opinion come with weak/daif chains. Where as the chains regarding permissibility are sahih. and this is the madhab of Shia

[Fath ul Bari, 9/150]

In urdu translation of Fath ul Bari, named Faiz ul Bari, it comes in Para 21, page 731-732

Same has been mentioned by Shokani in his book Neel ul Autar, 6/271

Sheikh Albany says

وجملة القول: أن ابن عباس رضي الله عنه روي عنه في المتعة ثلاثة أقوال:
الأول: الإباحة مطلقا.
الثاني: الإباحة عند الضرورة.
والآخر: التحريم مطلقا، وهذا مما لم يثبت عنه صراحة بخلاف القولين الأولين، فهما ثابتان عنه.
والله أعلم.

and regarding the saying of Ibn Abbas of what is narrated from him regarding Muta’a, there are three opinions
first, it was totally allowed
second, it was allowed when needed
and last, it was totally prohibited. and this is not proven from his clearly in opposition to the first two sayings which are proven from him
and Allah knows best

[Irwa Ghaleel, 6/319]