France is expected to deploy troops to Ukraine as soon as next week, in the capacity of "trainers." Nevertheless, these soldiers will clearly have a high bounty on their head by Russia.
This question will resolve YES if it is confirmed a French soldier was killed in Ukraine by Russia before the end of the year, by any means, including air strike. Official confirmation from the French, Ukranian, or U.S. government will be sufficient to resolve as YES. If the claim comes from Russia, conclusive proof will need to be provided as they have high incentive to fabricate it. Generally, any proof provided by Russia would need to be reported on and generally accepted by credible Western media sources.
This is more about if they are going to publish it. I don't think Russia wants to kill french soliders, just because they are french. I don't think frnch would publish it, even if someone is killed, because this would lead to an escalation, that could resolve into 3 World war. The odds, that af french solider is killed, is pretty accurate, but the chance that the French, Ukranian or US goverment would confirm it, is way lower.