COLRv1 font inconsistent color rendering

[vv-monsalve]

Describe the issue

A COLRv1 project, which includes gradients and transparencies, shows rendering issues on the Dev server.

It doesn't consistently display the colors; it seems to need the page to be reloaded since it only shows them after switching between tabs.

• The first preview after searching works ok

• But then on the Specimen tab
  

• The Type Tester and Glyphs tabs seem to be working well always
  

• Returning to the search results
  

To Reproduce
Enter the server and follow the above process

Expected behavior
For it to work consistently

Browser used: Chrome Version 123.0.6312.107 (Official Build) (x86_64)

cc @davelab6

[tomasdev]

Debug info: color is retained when asking a static instance like wght:400. Color is lost when asking for a VF subset like wght:100..700

[anthrotype]

Color is lost when asking for a VF subset like wght:100..700

maybe a bug in hb-subset

[davelab6]

Tracking internally at b/334968053

[davelab6]

This is confirmed as a problem with the API and the team is looking into it; Viviana has marked the family as blocked until this is resolved.

[vv-monsalve]

The family is being updated with an added Light color palette. It would be ideal for this fix to happen before the new font is ready. Is it feasible?

[davelab6]

This was because hb-subset did not support partial instancing of COLRv1 tables but @qxliu76 implemented it! :) so this should be all working in all envs now

[anthrotype]

Before and independently from fonttools! Good job Ginger!