When I click on "Browse wishlisted games giveaways" I can't see any giveaways.

Check that you have your wishlist at https://www.steamgifts.com/account/steam/wishlist
If it's empty - it's probably failed to sync, try to force sync your account at https://www.steamgifts.com/account/settings/profile
And if your list is there - then maybe no games from your wishlist are given away currently?

It probably means that there are no available giveaways for games from your wishlist.

Probably some problem due to syncing. Has happened to me as well sometimes.
Except if your wl is that small that there is currently no giveaway for the games on it.
I would put my money on the 1st case though.

Thank you very much, it was a syncing problem, it's fixed now. It was not very probable to have it empty as I have a stupidly long wishlist...