Okay here's the entire story
Around September 24th, when the new OS for mac Mojave came out, I downloaded and installed two brush bundles, the old Deevad one and the GDquest lite pack(but I didn't upgrade to mojave). I also downloaded krita v4.1.5. after installing the new krita and the brush packs, I started getting this problem where krita would expand random lines from wherever I was drawing, and after about a month it started getting really bad because the lines would extend to ridiculous lengths and were making the file size huge, (one got up to like 3GB) and slowing the program down. I spent two days trying everything to figure out
what the problem was, I tried krita v4.1.3, I tried deleting both the brushpacks I had, I tried downloading an updated driver from huion (i'm assuming, I downloaded the main one on the website but they don't have update numbers) and nothing worked. someone told me to use the tablet tester in configure krita and that showed that it would draw straight lines to wherever my pen was, at the same time as draw the actual line i drew. eventually I deleted my driver and anything huion on my computer, and updated my OS to mojave. when I opened krita again after installing a new driver, it seemed like the problem with the lines was fixed. the tablet tester was working fine, and so far I haven't gotten the line problem again. but this is where my pen pressure stopped working. It works completely fine on the huion driver pressure test, and other drawing programs detect the pressure fine as well. I tried krita with a wacom tablet, and it was picking up the pen pressure on that. now, for some reason when I click one of the buttons on the huion pen while using krita, sometimes it'll bring the pen pressure back. but it feels like the sensitivity isn't sensitive enough, like I have to press really hard to make it show up at all and when i press normally the line is really small, almost like the brush size shrunk? I'm used to using a brush size of 4.0 but now 12.0 is still tiny. then, when the pressure sorta comes back like that, drawing is incredibly slow. the lines are slow to appear and I THINK I might have seen a couple extending lines pop up again, tiny ones, but still.
i'm using a huion GT-191 tablet

Latest Update:
I've discovered that when I use the tablet tester on Krita it's detecting my pen as a mouse. When I click one of the buttons on the pen, it changes to detecting it as a device, but still not as a pen. Could this have something to do with why the pressure sensitivity isn't working properly on Krita?

but it feels like the sensitivity isn't sensitive enough, like I have to press really hard to make it show up at all and when i press normally the line is really small, almost like the brush size shrunk? I'm used to using a brush size of 4.0 but now 12.0 is still tiny

You can change it in Configure Krita -> Tablet Settings in the pressure curve window. Just drop the end point to the half of the height or even lower if needed.

I've discovered that when I use the tablet tester on Krita it's detecting my pen as a mouse. When I click one of the buttons on the pen, it changes to detecting it as a device, but still not as a pen. Could this have something to do with why the pressure sensitivity isn't working properly on Krita?

Exactly. That means that the driver doesn't work properly (which is no surprise considering it's Huion on Mac...) and Krita only gets mouse events (and mouse events doesn't have pressure information, because mouses doesn't have pressure sensitivity; only pen have those). When the driver works and recognize the tablet, it sends both kind of events: mouse and pen ones. Krita uses only the pen ones probably (unless they're not available), but in Tablet Tester you can see both of them at the same time in (mostly) the same location.

I can't help you with this, I would suggest writing directly to Huion, they know best their drivers and their problems (and possibly solutions).

Btw. I'm kinda a guest on this forum (I dislike it for various reasons) and I get that you didn't get any satisfactory answers yet, but making a lot of duplicate posts isn't the best way to go. I mean commenting your older post helps to keep everything in one place and at the same time higher it up in the posts list on the forum because of the time of the last post (at least I believe it works that way). No answers can mean that the issue is not descriptive enough and users don't know what to do or your issue is hard to solve and users don't know what to tell you.

Oh and disclaimer: not a Krita developer here.

Thanks for the info, i'm glad I at least sort of know what the problem is now. I'll contact Huion

Btw. I'm kinda a guest on this forum (I dislike it for various reasons) and I get that you didn't get any satisfactory answers yet, but making a lot of duplicate posts isn't the best way to go. I mean commenting your older post helps to keep everything in one place and at the same time higher it up in the posts list on the forum because of the time of the last post (at least I believe it works that way). No answers can mean that the issue is not descriptive enough and users don't know what to do or your issue is hard to solve and users don't know what to tell you.

Oh and disclaimer: not a Krita developer here.[/quote]

Yeah sorry to be annoying but I have to clue how to use this forum and no one was replying when I used the same post so I figured no one was seeing it. At least i've been getting replies on every new post.

I have this Huion pen buttons sensitive problem too. My new tablet is Huion Kamvas Pro 22. I am contacting Huion support.

They tested Krita 4.1.7 with Huion driver 14.7.60 on a PC and sent me a video as I installed them in my PC. Every thing is fine on the video. I do not know how can I attach that video to this reply. If you want to see this video, let me know how do I post it.

As I still have the problem with their pen buttons, they are working on this issue to find the problem for me. They understand that this problem concern lot of people.

If I move the pen to brush docker without touching the screen, click and hold the upper pen button on any brush then move the pen to the drawing area, release this button and click it again. Most of the time it works.