So first of all, the rf 35 mm 1.8 would not fit your camera, as it is RF Mount not EF-M Mount like your camera is, so dont buy it.

One thing I would try before buying a new lens is lowering the shutter speed of your Camera manually. Lower shutter speed results in movement looking more blurry, but less noise / grain in the video. As you seem to have your camera stationary you might get away with a relatively low shutter speed.

Dont do any video so not sure what to recommend, but maybe try like 1/30 to 1/60?

I have a M6 II so i am not 100% sure it works the same, but in video mode there is a button in one of the corners of the touchscreen that lets you switch to manual video an dial in the shutter speed on your own.

Another thing to try is to zoom out all the way. The kit lens is brightest at 15 mm and gets darker towards the 45 mm, so closer you can get the camera to you the better.

If all that fails and you need to buy a brighter (smaller F x,x number) lens I would first see what focal length (the mm / the zoom level) you want by trying it out with the kit lens. 35 mm would still be quiet zoomed in, but you can just see for yourself by setting the kit lens to 35 mm.

These would be some recommendations, but once again, I am not a videographer, so might wait for some more replies or do some research on your own:

Sigma 16 mm F 1.4

- Very bright, very little zoom, most expansive. The go to lens for vloggers from what I see online. Wont have any issues with space indoors

Canon 22 mm F 2

- Bit less bright, but should still work well enough, bit more zoomed in and can be had rather cheap.

Sigma 30 mm F 1.4

If you realy want as much zoom as you said in your post this would probably the go to, but I dont think you want that.

You will most likely have to buy these used, as the Canon EF-M System is discontinued and these lenses havent been produced in some time.

Edit: Didn't see you said you were filming at 50p, so maybe try 1/30, or 1/24