Cloudflare 502 errors today WPO Wordpress

Regarding error 502, kindly see suggestions from below articlces:

https://support.cloudflare.com/hc/en-us/articles/115003011431-Troubleshooting-Cloudflare-5XX-errors#502504error

May I ask have you had an SSL certificate before moving your domain/website to Cloudflare?
Also, if so, could you check what SSL option have you got selected under SSL/TLS tab at Cloudflare dashboard?

Here is a great step-by-step article how to propperly setup the SSL with Cloudflare:

To troubleshoot SSL, kindly check below article:

Some SSL settings to re-check, if so:

Maybe you’ve got some mixed content errors? Like loading HTTP resource over HTTPS?

May I ask which APO version are you using?
Maybe @yevgen could take a note here on this topic.

Kindly and patiently wait for another reply.