I use the client. Its far easier than opening zip files and exes. With that said I've noticed a few games in the client that just don't work when they do work outside of the client.
I set one of my free games to paid. Someone bought it and told me my paid game was getting flagged as a virus (via Windows Defender) by the client when it had not been previously when it was free. I had him download my other game... a free game and he said it downloaded fine and was not flagged as a virus when he downloaded it.
When I logged into the itch app I had to uninstall the game and when I tried to uninstall the Windows Defender threat detected popup happened.... when I was trying to uninstall it rather than install it. So I can't uninstall it. I went to a second computer and had the same results, but on the second computer it wasn't installed via the app, so when I tried to install it via the app there was a virus threat warning.
A friend of mine tried and had the same results.
I have uploaded a new .exe hoping that would fix it, but no. Maybe its just that one game / exe, but it never had threat warnings before.
This seems like a big issue.