Add color to toolbar icons.
The new 'Objects on a Path' tool has brought color to the toolbar. It now stands out a lot.
I have a bunch of plugins that add tools to the toolbar, and have a bunch of cryptic monochromatic icons. Perhaps it is time for both Adobe and plugin developers to bring some color to the toolbar so we have one more thing to help us remember which extremely specialized tool we use once in a blue moon is which?
(This also may require a switch in the prefs to revert to largely monochromatic icons for people who are colorblind and/or just hate change.)

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A lot of plugins use color accents, to stand out form the crowd of tools. The 'color brought to the toolbar' is most probably the blue dot Adobe apps use today to highlight a new tool or a function. This goes away once you try to use these. So it works to pull something out, and it works only because icons are monochromatic. Still it’s a choice plugin developers make on their own, there’s no rule or restriction applied but taste and impression planned.
At the same time, Affinity Designer gives a choice — to use color tool (and other) icons or two make them monochromatic.
It’d take a lot of effort to redesign these, but sometimes it helps legibility.