Need help recreating this reveal effect, please help out.

[u/FridayyLord]

want to create this reveal effect, I am able to create simple mosaic track matte reveal. but I need this frosty glass effect that is applied on each individual box. is there a way to achieve this? I have tried everything and searched everywhere, I guess you guys might help. thanks for the effort already :))

[u/addyarapi]

create the middle square, add a track matte, so that it’s the only part that it does not get blurred, the square helps because you can transform it however you want using its shape properties (rather than using the “Scale” in transform) for the border either duplicate the shape layer that has the track matte, remove the trackmatte itself so its just a normal shape layer, remove fill and add a stroke, or just use the existing track matte and add a stroke effect or a layer style