It looks the variant of 崁.

The evidence shows the character is used for the geographic name in the southern end of Taiwan Island. As the famous historical and cultural site, 赤崁樓 / 赤嵌樓, 崁 and 嵌 are common in Taiwan. If one character used for the common geographic names in Taiwan, TCA should handle this character well. In fact, this character has not been included in CNS 11643 yet.

Also see WS2021-00138 and 01060.

I still think it is dangerous to make the UCV for 宀 & 山 for our future encoding works.

Agree to comment #6670.
In addition, regarding the content of the evidence, in Taiwan, there is only "崁" in place names, "嵌" is rare, but there is no "⿱宀坎".
According to 陳正祥's statistics quoted in the evidence, the font should be "崁".

陳正祥，《臺灣地名手冊》(臺灣省文獻委員會，1959年)，P14.
https://tm.ncl.edu.tw/article?u=007_101_000009&lang=chn

I suggest China to withdraw the character.

It is included in 《八辅》

And the article doesn't say 赤崁 is written as 赤⿱宀坎 but 赤嵌. As to this article, the anthor just list all characters used as same meaning and then give statement about all of them .
What's more, it's used in Fujian Province too.

When we say if one character is used or useful for one place, the proponent must provide at least one piece of sufficient evidence. If not, I agree with Henry for suggesting China to withdraw the character based on the discussion result.

I think IRG encode not only characters used or useful for one place, but also characters used in books which can be schoolars' references. The shape in the evidence is clear enough, what's more, 山 and 宀 can be written as each other when used on the head of a character, so the shape is reasonalbe. So I don't think it should be withdrawed. Rejecting this character will only lead to a later resubmition.

李如龙：地名与语言学论集，福州：福建省地图出版社，1993年8月，P145

It is a print error. I will find another good evidence for the character and come back again.