U+FDF2 ARABIC LIGATURE ALLAH ISOLATED FORM is a very common ligature, used to display the name of God. When the formation of the allah ligature is desired, the recommended way to represent the word would be <alef, lam, lam, shadda, superscript alef, heh> <0627, 0644, 0644, 0651, 0670, 0647>. In non-Arabic languages, other forms of heh, such as
heh goal (U+06C1), may also form the ligature. Extra care should be taken not to form the ligature in the absence of the shadda and the superscript alef, as the sequences <alef, lam, lam, heh> and <alef, lam, lam, shadda, heh> exist in Persian and other languages with different meanings or pronunciations, where the formation of the ligature would be incorrect
and inappropriate.
Diacritics on اللّٰه اللّٰہ اللّه اللّہ are duplicated and mispositioned when shadda or superscript alef are explicitely in the strings
Diacritics are added to الله اللہ when they should probably not be added.
FDF2 ﷲ should be added and look like اللّٰہ because اللّٰه looks like it.
See https://w3c.github.io/alreq/gap-analysis/tests/ligation/ligation_000.html
See also Unicode 15.0 ch. 9: