I am not sure if those are clips or not, but the metal core looks more like zinc than copper to me. I am firmly in the "zinc" camp unless the 2.5 gram weight is wildly inaccurate.
The color on the cut edge might be tarnish, a foreign substandard, or a pale shiny surface reflecting the colored light bouncing from a nearby colored surface. It looks paler than the copper surface, to me. It also has the grainy appearance of a broken off piece of zinc.
As far as weight... Allowing for tolerances in the weight of a zinc LMC
(plus or minus 0.13 grams) plus the uncertainty of the measurement of a scale that only measures to the nearest 0.1 gram (something + or - on the order of the last decimal place is a good place to start in the absence of calibration data or specs) a measured value of 2.5 grams for a clipped zinc LMC
seems to be within the range of what we could expect. That uncertainty would account for the 0.1 - 0.2 grams (by my experiment above) or so of material that is obviously missing. So, that can explain the OP's measured weight of a 2.5 gram for a clipped zinc cent without invoking a paint hypothesis or anything else, but it won't reach far enough to cover the bronze planchet hypothesis.
This amount of effort expended on this subject is probably overkill, but I'd rather do math, read about coins, and perform experiments than work on my taxes, so the rest of you are just going to suffer my ramblings.... Please forgive me.