Regarding Cults; I think I found the issue.
In v7 the default values for Fertility Cult were 0.1 Food and 0.04 Culture per resource (as shown on the menu Civilopedia screen), becoming 0.3 and 0.12 when playing the XXL 35 scenario.
In 7.12a the base values are still 0.1 and 0.04, but when playing XXL 35 they become 0.05 and 0.02. XL and XXXL scenarios have the same values. This is why no Cult will ever get more than 1 in any bonus, even with 20 resources they won't multiply to more than 1.
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Related suggestion:
The change to a maximum of 20 resources was great, since before cults were overpowered when played on larger maps. However instead of a flat maximum of 20, would it be possible to have the maximum based on map size and require more resources to hit the same values? This would prevent cults from becoming overpowered again when playing a large empire on a small map.
For example; if the max Food produced by a cult is intended to be 5 per city, on a very small map the max would be 5 resources producing 1 each, a huge map would have a max of 40 resources but each would only provide 0.0125 (numbers not balanced in any way, only used as examples).