It’s not just Muslims who have multiple wives in India. But practice has declined across faiths
Only 1.4% of married Indian women surveyed in NFHS-5 (2019-2021) said their husbands had another wife or wives. Practice more prevalent in tribal-dominated districts. https://theprint.in/india/its-not-just-muslims-who-have-multiple-wives-in-india-but-practice-has-declined-across-faiths/1578799/
https://www.indiatoday.in/india/story/women-rights-group-releases-book-polygamy-asks-for-criminal-action-2311620-2022-12-21
The book 'Status of women in polygamous marriages and need for legal protection' is based on a survey of 250 Muslim women. Dr Noorjehan Safia Niaz,
Many victims of polygamy were also present at the book launch. Irfana Qureshi, who is a one such victim, said, "After marriage, I got to know that my husband was married twice before. I had to go through domestic violence and torture.
Regarding the mental health of those in polygamous relationships, the survey revealed that 50% women suffer from mental trauma such as depression, self-blaming and suicidal tendencies.
FM on WA: That's the voice of the Muslim community that needs to be heard. From Equal Property Rights, to Halala, to Child Marriage, to the imact of the law on Instant Triple Talaq, and many others issues
SS on WA: The higher percentage in the case of Christians is presumably attributable to the fact that large sections of Afivasis/tribals -- those in the North-East in particular -- are Christians.
What's significant is that while polygamy is prohibited for Hindus (and, by extension, Sikhs, Buddhists and Jains) a certain %age of polygamy has still been reported. Maybe, here, we have a bit of under-reporting.

https://theprint.in/india/its-not-just-muslims-who-have-multiple-wives-in-india-but-practice-has-declined-across-faiths/1578799/ “Before arriving at any conclusion based on the social, economic and demographic characteristics, one has to bear in mind that the prevalence of polygyny in India is low and it is fading away,” it concludes, adding that the demographic health and gender consequences of polygyny need further investigation.

https://www.indiatoday.in/india/story/women-rights-group-releases-book-polygamy-asks-for-criminal-action-2311620-2022-12-21
The book 'Status of women in polygamous marriages and need for legal protection' is based on a survey of 250 Muslim women. Dr Noorjehan Safia Niaz,
Many victims of polygamy were also present at the book launch. Irfana Qureshi, who is a one such victim, said, "After marriage, I got to know that my husband was married twice before. I had to go through domestic violence and torture.
Regarding the mental health of those in polygamous relationships, the survey revealed that 50% women suffer from mental trauma such as depression, self-blaming and suicidal tendencies.
FM on WA: That's the voice of the Muslim community that needs to be heard. From Equal Property Rights, to Halala, to Child Marriage, to the imact of the law on Instant Triple Talaq, and many others issues
https://theprint.in/india/its-not-just-muslims-who-have-multiple-wives-in-india-but-practice-has-declined-across-faiths/1578799/ “Before arriving at any conclusion based on the social, economic and demographic characteristics, one has to bear in mind that the prevalence of polygyny in India is low and it is fading away,” it concludes, adding that the demographic health and gender consequences of polygyny need further investigation.