There is nothing wrong with an accessibility toolbar. We have been using them since 2006 when we built our first accessible website to WCAG 1.0 AAA standard. The key difference is that ours were built into the code. Commercial toolbars load large amounts of code from external servers when activated, and that is where the problems begin.
They may help with WCAG 1.4.8 Visual Presentation, but that is a AAA criterion. It sits outside WCAG 2.2 AA, which is what the Public Sector Guidelines and most laws around the world require. In other words, overlays do nothing to help a site meet compliance.
Whether you are planning a new website, reviewing an existing platform or trying to understand your accessibility obligations, we would love to help.
Please get in touch to discuss your project, accessibility goals or digital challenges.