As I try to enter an amount of EUR to swap, it changes to a smaller number, what is the issue?

The amount might automatically adjust to the maximum allowed based on the 30 day moving window limit. Note that any swap attempt will be deducted from the limit. It doesn’t matter if the swap succeeded or failed or was manually cancelled. The limit is reduced by the corresponding amount as soon as you click on the “Confirm Swap” button, in order to protect against atomic swap spam attacks.