IBKR behaves weirdly when converting currency and immediately buying with a cash account

[donato]

@ma0

However, please note that the conversion rate applied by IBKR may be adjusted from the standard market rate to account for any differences between the settlement cycle for your stock trade and the typical settlement cycle for that currency pair. This rate adjustment allows IBKR to manage the associated risk and costs.

Apologies, I just posted in the other thread but I see that the conversation has picked up again here… Can anyone explain what the “however” means in practice? Thank you!!