From my understanding of mobile-first indexing, your mobile site will become the primary version Google crawlers see when they are looking at your website. So in terms of the impact of hiding the breadcrumbs on your mobile site, Google will see that you've hidden them and may or may not see them on the desktop version because they may or may not bother to crawl the desktop version.
My question to you would be - what value are you seeing from the breadcrumbs on desktop? Can you check your analytics data to see whether users are using these breadcrumbs for navigation? Do you mark up your breadcrumbs with schema to allow them to show up in rich snippets? If the breadcrumbs do not currently add much value to your users and if they don't serve an SEO purpose, you may not need to bother including them on mobile. On the other hand, if you know that they add to a better UX, you may see a benefit from adding them to the mobile version of the site. This is because Google likes to reward sites with a better UX for mobile users. If you are using them more for search engines to have easier crawl access, I would suggest revisiting your site structure more broadly to ensure that no important page is further than 3-4 clicks from the homepage; and/or ensure that you keep your sitemaps up to date with all important pages and submit in GSC and BWT.