Checked server load - minimal
Other users can access the same site fine
Users who experience HTTP 522 going through Cloudflare are able to reach our site if Cloudflare is turned off or by the IP address
What are the steps to reproduce the issue?
Difficult to reproduce as it is only affecting some users
From everything you’ve mentioned in your post it seems very likely that those users may have some restrictions on their end that could be preventing them from accessing your website.
Please confirm with your users the following:
VPN with custom profiles that could be blocking the traffic from your website
Possible connection issues with their ISP (a simple router reset or restart could be a fix)
If all the steps above don’t result in a fix, you will probably have to add their IP addresses to your cloudflare IP manager.
You can manually add their IP addresses to your allow list so they can access the website to bypass any sort of block that their devices, ISP or any other third party interference from happening.
In addition to that you can also check that youtube video that gives you a few tips on how you can get this issue sorted out:
