https://www.techpowerup.com/267757/psa-there-are-two-steppings-of-non-k-10th-gen-core-i5-in-circulation-only-one-comes-with-stim
 
There are apparently two steppings of the 10th generation Intel Core i5 desktop processor in circulation, and the two have major physical differences, even if their specifications are identical per SKU. These are Q0 and G1. The Q0 stepping of the 10th gen Core i5 is based on the 10-core variant of "Comet Lake-S" silicon, the 200-odd mm² die, which comes with Intel's die-thinning innovation, and more importantly, soldered thermal interface material (STIM). For these chips, four cores on the 10-core die are disabled by Intel to carve out the 6-core/12-thread Core i5 SKU. The G1 stepping, on the other hand, is based on the 6-core variant of "Comet Lake-S," which is similar in design to the 6-core "Coffee Lake" die. The G1-stepping chips lack STIM, and use a thermal paste.

What's more, Q0 and G1 steppings have different SPEC codes. For the Core i5-10400F, the Q0 stepping variant's SPEC code is "SRH79" and the G1 stepping variant's code is "SRH3D." The underside of the processor's package looks different between the two steppings (pictured below). You won't be able to tell the underside of the package through the little window in your processor's retail package, but the SPEC code is printed on the IHS. There's no geographic marker as to which stepping is found in what particular market. Both steppings appear to be distributed uniformly, wherever available. Since Intel is using this stepping-level differentiation only among non-K SKUs, we don't expect the two to have any different performance, but possibly different thermals.
 
Personally I find this very confusing.
 

Who really cares? Neither of those models are unlocked for overclocking so I'm sure regular thermal paste is fine for them.