Currency divergence

Wasn’t quite sure where to ask this but, how is value tracked within the app when the driver of gain/loss is currency divergence? For the purpose of the question I’m ignoring all FX fees and taxes.

Let’s say I buy £100 worth of US shares tomorrow at a rate of £1 = $1.35. At some point in time in the future, the rate is £1 = $1.215. But the shares that I’ve held since buying happen to still worth be worth exactly the same, $135.

Obviously if I were to sell them at that point I’d receive more in GBP, and at that point any profit would reflect in the total gain/loss of investment. But if I don’t sell them, how will those shares’ performance track in the app?

The value reflected is always converted back to GBP at the current rate so you would see the changes in FX in your valuation.