Since a deposit does not generate a cost base, but gift / income do, it might seem like an easy way to eliminate tax report warnings by renaming the transactions.
However this can - in the worst case - result in tax fraud.
Here is an example:
You buy 1 BTC for 3000 Euro, but forget to enter that trade.
Later, when the BTC is worth 4000 Euro you transfer it. This transfer is imported by an exchange and in order to correct your numbers you change that into a gift. Now this BTC has a cost base of 4000 Euro according to the gift time stamp.
Next you sell that BTC for 3800 Euro.
The software will calculate a loss of 200 Euro for that sale instead of a gain of 800.
If you report this number to the tax authorities, you are in trouble (if they find out).
The only correct way to correct the warning for a deposit is to enter the original purchase trades of the transferred coin.