Turn on screenshots before creating an analysis and find out how pages are rendered.
When running a SERP Analyzer query, you can enable a Screenshots option.
Screenshots can be then found under the three dots icon:
Screenshots provided by Surfer will show you how the our or Google bots see your or your competitors' pages. They have limits at 10k pixel height so you will see much more than in the basic analysis provided by other tools.
The quality of your page and the responsiveness might affect your rankings, but often they depend on the device being used. To see what the problem could be, checking the screenshots might be able to provide you with some insights.
Additional resources:
Surfer Knowledge Base