Please advice.

I found an old wallet.dat file with BTC X.98  (X number of whole bitcoin pluss .98)

I load the entire Bitcoin Core and start it up.
I swap the native created wallet.dat for my old wallet.dat file.
The balance of X.98 comes up.

I then first make one small test sending to my safe Ledger wallet address (legacy wallet) of 0.0001 bitcoin, where transaction fees are to be withdrawn from amount.
The sending is done in the Bitcoin Core wallet (confirmation set to 2 blocks), but it does not arrive at the Ledger wallet.
But I see that the balance of the wallet has gone down from X.98 to X.96. so down BTC 0.02. But I think maybe thats just some kind of rounding error.

So I make another small sending this time of 0.003.
It get sent, but does not get received.

But this time the balance is down to X.91     so balance is down BTC 0.07 by just sending these two very small dust sendings.
That is USD 4000 of bitcoin just to make two very small dust transactions.

How is this even possible.
Do I have some kind of setting that is eating BTC?
Is there something with my old wallet?
(I have tested multiple old wallets like this, can settings from one wallet transfer over to another and mess things up?)
Might I have been hacked somehow (im on a pretty new MacBook Pro)

its just very weird.

Any advice much appreciated.
Thanks.