What is this on Maple leaf

[Haplo]

What is it

 

[Haplo]

I know they're galls, but what specifically?

 

[Del_]

Might be:

Maple Spindle Gall Mite (Vasates aceriscrumena)

 

[lone wolf]

https://extension.psu.edu/leaf-galls-on-maple

 

[diver64]

Might be:

Maple Spindle Gall Mite (Vasates aceriscrumena)

Looks like that to me