My partner has several visual disabilities that make using Zoom difficult regardless of the platform, and she’s not alone here.
For individuals with certain kinds of colorblindness, the choices of medium light blue, white, and light grey are very difficult to see. Alternative schemes to make things more visible are needed, whether it is a choice of stock or high contrast (at a minimum), or a roll your own scheme. Not all devices support color correcting “themes” correctly, if at all.
Individuals who cannot distinguish between red and green, may not know when a feature is active or inactive if the color changes. Hollow with a slash vs filled may not cut it either in certain conditions. A lit/unlit (i.e. filled icon/hollow button = off/ hollow icon/filled button=on) method works better. At that point, colors don’t matter.
For individuals with poor visual acuity, there needs to be a method for changing the size and weight of text and icons. 1-2px wide outline icons are not suited for this, as they can fade into oblivion. This is another example for where lit/unlit buttons address the issue and colors don’t matter.
The U.S. General Services Administration (GSA) published some accessibility standards for web/internet applications (aka Section 508). I’ve worked with them in the past and can say firsthand that they are worth reviewing and applying; it’s not as difficult as it sounds.