This is either cache plugin conflict or a conflict with some JS optimizer plugin, it could be minimized and optimized by Jetpack as well. Here is a similar case: https://gvectors.com/forum/postid/33335/
First, please make sure the profile pages are excluded from your cache plugin. wpForo 2.0 profile pages have new root path, so you should exclude them as well. Please find your cache plugin from this list and do the steps to exclude all paths: https://wpforo.com/community/faq/wpforo-and-cache-plugins/
Then delete all kind of caches and purge CDN if you have.
If the issue is not resolved, you should find the plugin or an option of a plugin which optimizes or minifies JS files. It should be disabled on for wpForo JS files or for the profile path: /participants/.