This design of the Sliders in GIMP 2.99 is not good.
I don't know if this design is temporary until 3.0 is released, but if in doubt, I decided to talk about it.
This + and - symbol is very ugly compared to the current design of 2.10.18, which is much more subtle.
There is no contrast between the slide and the rest of the layout, and it confuses everything.
There is no need to add a space on the slide itself to increase the brush size with small steps, since it is now possible to do this with the right mouse button.
These are my observations, I hope this will be in this version of GIMP temporarily. If it is to change to something worse, better leave it as it is, it is already good.