Fira Code font spacing looks narrower in the new versions of JetBrains IDEs

Problem

The character spacing in the IDE editor with Fira Code font is different between different IDEs.

Cause

The font rendering for Subpexil antialiasing was changed between the different versions of JetBrains Runtime.

Resolution

Changing the Settings | Appearance & Behavior | Appearance | Antialiasing | Editor option to Greyscale solves the problem.