Private Messaging broken on tradera.com (due to Focus ad blocking?)

This happens right away in Firefox Focus for iOS when trying to access https://www.tradera.com/messaging (required sign-in. Tradera is a Swedish Ebay equivalent) and makes it impossible to communicate with sellers and buyers. It also happens in Safari when the Firefox Focus content blocker extension is enabled. Disabling that makes the page work. I also have AdGuard and uBlock Origin Lite Extensions, and they do not break the page. The issue is not present in the standard Firefox for iOS app. Suggestion: whitelist the /messaging subpage, there are no ads there anyway. The rest of the site is pretty ad-ridden.