Mobile CVR is often half of desktop CVR. Most brands treat that as expected rather than as an optimisation problem.
Some of the gap is real intent. Mobile buyers do browse more than they buy, especially in luxury or high-consideration categories.
But mobile traffic share has passed 60% for most ecom brands, and buyers who start on mobile don't always switch to desktop to complete. A 50% CVR gap usually has more to do with the experience than the device.
Session recordings on mobile-only traffic surface the same patterns:
Address field drop-off in checkout, often because the input doesn't trigger the right keyboard.
Pinch-zoom on PDP copy because the body font is below 16px.
ATC button below the fold on mobile, even when it sits cleanly above the fold on desktop.
Tap targets under 44pt that get mis-pressed, especially on size and variant selectors.
Most of this comes down to form friction and content legibility. Both are testable, and both have low-cost fixes.
Tools that surface mobile-specific issues: Lighthouse's mobile audit, mobile-filtered session recordings in Hotjar or Clarity, and PageSpeed Insights for mobile Core Web Vitals.
If your mobile CVR is less than half your desktop CVR, I'd start there before testing anything else on desktop.