english rules question: if G before i/e/y, is pronounced as jee,

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english rules question:
if G before i/e/y, is pronounced as jee,
then why do we say girl and not jirl?

the question was thought of when discussed if the pronounceiation of GIF is jiff or giff.

imo, since its an acronym, there are 2 ways to read it:
1.as a word
2.each letter seperately.

in the 2nd case its simply saying the letters names (wtf= doubleyu tee eff).

but as for the 1st case, since we read the acronym as a word (lol, gif, etc), it is understandable we need to apply the rules of orthography, thus pronouncing "g+i" as jee, therefore, its jiff.

but then again, why is it girl and not jirl?