Hi - I just wanted to chime in that I'm also having this problem, and have never NOT had this problem in the 4 years I've been using a Wacom tablet. Honestly I just thought I had been doing something wrong or had a crummy keyboard, but after replacing it and upgrading my computer, the issue persists. Validating to see that I'm not the only one experiencing it, but also it's absolutely infuriating that after so many years this problem is still present. Like literally all this thing needs to do is be a pen. It has all these silly features that professionals do not use, and the one feature that we do need, for it to just be a #%#$%$ pen and not interfere with Photoshop's basic, core functionality, doesn't work and hasn't worked for HALF A DECADE. I am honestly hard-pressed for words.
I'm running the latest Catalina with the latest PS and latest Wacom driver. I've tried uninstalling with the Wacom utility and reinstalling to no avail. The exact issue is that when I use CTRL+ALT to change brush size and hardness, CTRL does not release, and I have to press it again to get back to drawing. However infuriatingly, it does not exhibit this behavior every time the key combination is pressed, making it impossible to know if the key is stuck prior to drawing. As someone who spends hours in Photoshop every single day as part of their job, I just want to say that finding out after all these years that this was some stupid Wacom bug that you all have known about for YEARS makes me want to set this tablet on fire. I don't know what other information I can provide. I'm speechless that Wacom does not have even just a handful of full-time, professional photographers with beta or RC versions providing feedback about this. Literally any photoshop professional would be encumbered by this bug. This is like a court stenographer who types all day every day having a SHIFT key that doesn't fully release and half the time they press it, it types in all caps and they have to backspace in the middle of their work and start the sentence over again. Do you really think they would not be furious to have to use a keyboard like that?
Anyways. Sorry for the rant but I just am totally shocked that this is actually a bug with the tablet and that you all have known about it for years. If this isn't fixed shortly I will absolutely switch to another brand, using a tablet is a huge part of my work and if I have to pay $200 to make this stupid bug go away it would 100% be worthwhile.