Resize before screenshot causing flaky tests

When I run the debug window, I've noticed that there is some kind of resize happening before screenshots are taken. This is okay for most tests, but I also have certain scenarios with components which animate when resize is triggered. For these specific scenarios the screenshots are inconsistent and therefore the tests are flaky.

Is there any way to stop the resize? I'm currently looking through the source code for backstop but I don't see a specific resize happening. I think the resize event should happen before everything everything else is run so that the page has time to settle.

I'm running this in docker.
My config:
```
var config = {
id: 'myId',
viewports: [
{
label: 'desktop',
width: env_config.viewport.width,
height: env_config.viewport.height
}
],
onBeforeScript: 'puppet/onBefore.js',
onReadyScript: 'puppet/onReady.js',
scenarios: [...myScenarios],
paths: {
bitmaps_reference: 'src/bitmaps_reference',
bitmaps_test: 'report/bitmaps_test',
engine_scripts: 'src/engine_scripts',
html_report: 'report/html_report',
ci_report: 'report/ci_report'
},
report: ['browser', 'CI'],
engine: 'puppeteer',
engineOptions: {
waitTimeout: 90000,
gotoTimeout: 300000,
headless: true,
args: ['--no-check-certificate', '--disable-dev-shm-usage', '--no-sandbox']
},
resembleOutputOptions: {
ignoreAntialiasing: true
},
asyncCaptureLimit: env_config.baseURL.includes('http:') ? 1 : 3,
asyncCompareLimit: 50
};
```