In the fatwa, it is mentioned that Abu Qatadah رضي اللہ عنہ hunted a wild donkey. Some Companions ate its meat, while others did not. When they asked the Prophet ﷺ about it, he said that it is a food Allah has made halal. This hadith is in Bukhari (1821).
Based on this, Islamic scholars say that hunting and eating wild cow and deer is also halal. Imam Nawawi رحمة الله عليه listed wild animals like wild cow and deer as permissible. Allama Shirazi also said that wild deer and wild cow are from the good and halal foods, and they may be hunted and eaten.
This shows that the Islamic ruling is clear: their meat is allowed.