מותר להטמין חמין מערב יום הכפורים למוצאי יום הכפורים: הגה וי"א שאין להטמין ביום הכפורים (עיין בטור) וכן המנהג במדינות אלו (מהרי"ל):

“Keeping food warm⁶⁶ be assumed that food could be kept warm on Yom Kippur by means of a continual fire on Yom Kippur, which is not permitted. on the Eve of Yom Kippur” - Containing one paragraph. It is permitted to keep food warm from the Eve of Yom Kippur until the end of Yom Kippur. Hagah: There are those who say that one is not to keep food warm on Yom Kippur (see in the Tur, טור),⁶⁷, טור; see footnote 23. and so it is the custom in these lands, (מהרי״ל).⁶⁸, מהרי״ל; see footnote 8.

footnotes: ⁶⁶ Keeping food warm on Yom Kippur refers to putting food in an insulated container that was usually a box of some type surrounded by wool or old clothes. It should not ⁶⁷ Tur ⁶⁸ Maharil