If you're playing the game on itch.io they are no longer supporting it. Some people can't or won't use Steam for various reasons (medical problems verified to be caused by the Steam client in my case). If you're fine with Steam though, you can get a Steam key from the "download" page on itch.io if you bought the game here. If you aren't willing or able to move to Steam, contact the devs, give them another voice telling them you want the itch.io version supported (more people telling them this means they're more likely to actually care) and contact itch.io for the refund. I got mine organised a couple of days ago and the money back today.
Here, have a topic on the Steam forums posted by one of their own moderators to direct the conversation (and keep it out of the front lines by putting it into the "beta" forum instead of where it actually belongs since it's the live build of the client causing issues):
https://steamcommunity.com/groups/SteamClientBeta/discussions/3/2962768084999962...
It has links to a number of prior discussions about the topic, dating back to a few days after the launch of the new library. I consider it lucky that I happened to be in just the right frustrated state over the situation (not realising Steam was causing it) to go "well it's OBVIOUSLY NOT this, but can't hurt to rule it out properly" when I heard someone else suggesting Steam was causing health problems for people. And in spite of going in with the expectation of proving the claim wrong (at least in my own case), I ended up having it verified instead.
And in the more than 18 months they've known it's a problem, Valve have made only one change affecting the customers dealing with the issue, and that was to block access to the only safe workaround we had for the first few months.