Currently the mask values option (Settings menu->Mask values) hides the wallet balances shown on the Overview page including the recent transactions list from the right panel but it doesn’t hide the amounts from the transaction view.
This enhancement has been mentioned on PR #701 as a desirable follow-up.
First approach was to hide the amounts on the transactions view when mask values option is checked:
But later on as reviewer furszy recommended, I’ve disabled the Transaction tab directly and switch to the Overview tab if the mask values option is set, check the new screenshots in the comment below.