Looks like that base gasket mighta been slightly bent over a shelf edge or something like that, and since it's fairly thick and rigid, it didn't bend or crease but instead kinda roughly cracked/delaminated.

I'd dress any carb base gasket with a light surface coat of Permatex #85420 anyway, which should press together and seal up that rough streak nicely enough to do its job just fine.

Don't dress that other paper gasket tho', since you may need to be able to pull off the carb top now and then to swap main jets for tuning, or service the needle valve or float, and that doesn't really need to be a fully airtight seal anyway since it's above the throttle butterflies.