When you click to save the attachment, it is stored in your selected download folder. If you click to open the attachment, it is stored in a temporary folder. To do both, when viewing the opened PDF, click file>save to store in the desired folder. I do not use MAC, but this may reflect a change, as I worked with another person with same question yesterday.

I'm on a Mac, and running same version as OP.

I just noticed the same issue. The problem is the lack of consistency. If I'm opening a PDF, then fine, I can do as you suggest above; even though it's an extras step that we didn't need to take before.

But when opening a word doc, we still get the same dialogue box as usual: 'Open with', or 'Save file'. In the past, they both ended up in the same folder - the one you selected in your prefs. But now, the 'Open with' sends the file to some hidden god-forsaken folder. If I hadn't been searching for a specific doc, I never would have noticed that the files weren't being saved where I want them to be saved. Thankfully, Mac runs an amazing search function and we're able to find the missing docs. But the basic point here is that there can't possibly be a good reason for sending the files to a temp folder. This didn't happen before now. Please end this.