Seems like a fundamentally unsolvable problem. These techinques use a spectrum of colours for deeply nested brackets. (If you only have one or two levels of brackets then you don't need the colourisation in the first place.) But colourblind users fundamentally don't have that many choices of colours to pick from in the first place.

Modus Operandi provides accessibility options for colored bracket pairs in Emacs out of the box.

I use a space indent colorizer plugin that I use a grey scale color scheme with.

It isn't a complete replacement for bracket colorization, but it helps in a lot of cases.

(Not colorblind, I just prefer a grey scale theme for my indent reminders!)

Maybe they could use a superscript or subscript number instead?

It's not unsolvable. Colorblind people are missing one axis of color (such as the red-green axis). It is perfectly mathematically possible to pick colors that do not only differentiate along this axis, hence this option in many AAA games.

Here's an online simulator to see what colorblind people of various types see. Note that if you yourself try this and the colors for one of the examples don't seem to change from the "normal" version, see your eye doc...

https://daltonlens.org/colorblindness-simulator

just the ability to change the bracket colors with reasonable default selections for colorblindness seems like a more than reasonable request

I’m not colorblind but I would wholeheartedly agree because I know colorblind guys

The extension already had a setting to tune the color palette even before it was merged into VSCode core.

This might be my own personal experience, but one effect of my colorblindness is that I place far less emphasis on color-coding in the real world--I'll subconciously ignore things like status indicators. When I think of alternative solutions here, I tend to reach for variables like font weight instead.

Any interest in working together on a new extension?

What would be the possible solution ? Change size ? High contrast fg/Bg combinations ? Special UTF characters?

Subtle distinctions in font weight or italic-ness? Variable fonts give a lot of options.

Mathematic notation uses subtle tweaks/additive glyphs to the same characters all the time.

A different spectrum per type of colorblindness. It should work fine, unless you're completely blind to all colors, which is a very small proportion of colorblindness, most are only lacking perception of one out of three colors.

You can already do that: in the settings.json under workbench.colorCusomizations, change editorBracketHighlight.foregroundX where X is the level of bracketing you want to modify.

In practice, though, the reduced color vision combined with the small target that is a bracket (color vision degrades for smaller objects), means that this is of limited usefulness.

See XKCD: "How standards proliferate".

No, that's not relevant and I think you know it, funny man

Can't you just define the symbol color pallet in options? (I'm not a vscode user, I use JetBrains and I just define my own colors)

You absolutely can define your own colours. You can even have different colour pools per bracket type ([] () {}) if you want.

Given that colour blindness is a wide spectrum, I don't know what more people expect VS Code to do here?

Your chosen theme decides the original colours, then you can override them. Isn't that enough?