Figure out why Lighthouse score drops after v12.1

[gabalafou]

Newer versions of Lighthouse cause our performance score to drop below threshold (80%).

This is preventing us from updating the Lighthouse GitHub Action that we use: treosh/lighthouse-ci-action.

Cross references:

• Set treosh/lighthouse-ci-action to 12.1.0 #2223
• Bump treosh/lighthouse-ci-action from 12.1.0 to 12.6.1 #2230