So this has been an issue ever since I started playing coc like 7-8 years go, It is still an issue right now. There always a kid in the clan who donates wrong and hes probably too smart to be caught unless we kick everyone who has the same level of units.
What am saying is, add a donation record for each player for like an hour or two (just like we have the data for who we attack and who attacked us in the battle log), which is visible only to an individual player(not displayed to the clan chat, as it probably create a mess). So we could kick the culprit out. Some people probably gonna be like it is just a donation you could always request again, but I don't think it is that easy.
For example in our clan people are leaving cause of a certain someone we can't find who is donating wrong, as there are so many who has the same level of units, it could be anyone, and one day the clan will be dead. It is just raising toxicity within the clan and is not healthy for clan.