Balance of account


When I look at balance of my Invest account, at any point there is a difference of around 3 pounds. I can appreciate it’s not a huge amount difference but just like understand this, am I missing something?
There is no pending orders or positions.

Deposit 16536.91
Dividends 7.92
Return 5.09
Total: 16,549.92

Invested 15868.75
Free funds 677.73
Total: 16,546.48

Thanks in advance.

Could it be due to the FX?

Stamp duty on trades?

Is there a stamp duty on foreign trading ?
Not sure if it is some hidden fees?

Stamp duty applies only to UK stock.

There are no hidden fees.