Alejandra normally has strong opinions around where spaces should and shouldn't go, but in the case of attrset access (eg. foo . bar, it doesn't change the spacing at all:

$ echo ' {   a     .   b    =   {     } ;   }' | alejandra -q
{a     .   b = {};}

I would expect the following output:

$ echo ' {   a     .   b    =   {     } ;   }' | alejandra -q
{a.b = {};}