There's this Prerequisite / Assumption / Risk in the Draft Technical Design document:

Spectron (Electron's testing framework) is not very well maintained, has already got problems with the version of Electron we're using that necessitated disabling our E2E tests on Windows and is going to be officially deprecated in the new year. The test framework that supports Electron with all the momentum at the moment is Microsoft's Playwright, so we should move our existing tests to that before writing even more tests that would also have to be ported when we switch.

We better test that Playwright is viable and will work with our version of Electron on all our target operating systems before we start.