I always topped up my Revolut card using a bank transfer as there was a charge for a credit card top-up. However, the bank transfer meant that the transfer wasnt instantaneous. Today, I topped it up with the credit card and they appear to have done away with the charge.

Not entirely. There is a warning on the site that some charges may still apply. It has been updated recently.

https://www.revolut.com/help/getting...ing-up-by-card

Full thread on Revolut is here:

https://www.englishforum.ch/finance-...d-revolut.html

The fee that one is charged for topping up with a credit card is clearly marked underneath the amount one decides to top up with. On this occasion it was clearly marked 'no fee'. It's new. I used the same credit card I always use.