Nancy correctly related that Photoshop needs more gigabytes of free space than you have on your drive, and it's telling you so.
If you didn't have the problem before, well, that's because you probably had more free space (certainly a few gigabytes more at least before installing the latest version of Photoshop). There are a couple of things you can do, such as reduce History states in your Performance preferences.
But the most appropriate suggestion, to be very honest with you, is to upgrade that SSD to a model 2 to 4 times bigger if you want Photoshop to run well. Yes, that's what Photoshop needs.
FYI, right now I have 838 GB of free SSD space. I've seen the it go down to as little as 500 GB free when doing a Photoshop Photomerge panorama stitch.
-Noel