@Tgr -- I made this separate task so that you and @Dyolf77_WMF can look into this. The ambassadors will also be testing the module in production this weekend in T243026, so we might hear more on this front.

Here are two example queries (topic=arts, 10 results): production, beta

Comparing those:

$ test_growthtasks() { curl -s "https://$1/w/api.php?action=query&format=json&generator=growthtasks&utf8=1&ggttopics=arts&ggtlimit=10&ggtdebug=1" | jq --raw-output '.query.pages[].title' | sort; }; 
$ test_growthtasks ar.wikipedia.org
ابن البيطار
ابن غطوس
الوطن العربي
تذهيب الكتب
جلال أمين صالح
خط الرقعة
خط كوفي
غزة
لغات أمازيغية
محمد حسني (خطاط)
$ test_growthtasks ar.wikipedia.beta.wmflabs.org
ابن البيطار
ابن غطوس
الوطن العربي
تذهيب الكتب
جلال أمين صالح
خط الرقعة
خط كوفي
غزة
لغات أمازيغية
محمد حسني (خطاط)
$ diff <(test_growthtasks ar.wikipedia.org) <(test_growthtasks ar.wikipedia.beta.wmflabs.org)

there's no difference.

I don't remember exactly when this was reported so maybe we changed something since then.

@Dyolf77_WMF do you have an example from the API sandbox where beta and production give different results for the same query?

@Tgr I used the SE module in beta to look for the suggestions not the API, and found that the results are quiet different from the production (API). Today when I went back to beta to check again, the SE module didn't show topic selection. So I tried with API in beta and the result seems as good as in API production.
Now, after testing in production as in T243026, I found the results not so good as in API test, for example when selecting Arts, yes the list above you found is good (9/10) but the SE module is showing less good results: (4/10).
I mean the results from API and SE module are different.

The module uses more random results (roughly identical to using the API with gglimit=250 instead of 10, ie. top 250 results instead of top 10), to avoid all users who select the same topics getting the same tasks.

Thanks for the explanation @Tgr

The module uses more random results (roughly identical to using the API with gglimit=250 instead of 10, ie. top 250 results instead of top 10), to avoid all users who select the same topics getting the same tasks.

I think this comment resolves the task, but moving over to QA for @Etonkovidova and @MMiller_WMF to look as well.

In T243035#5814967, @Tgr wrote:

The module uses more random results (roughly identical to using the API with gglimit=250 instead of 10, ie. top 250 results instead of top 10), to avoid all users who select the same topics getting the same tasks.

I re-checked with couple of topics and although, of course, evaluating relevance is subjective, when the number of articles is the returned set is limited - the suggested articles from betalabs and from production match entirely.