We have noticed this issue yesterday as well on our site. Once the site was refreshed the error went away but we have done a SSL check and have noticed that one IP is not verified.
Link to the report here → SSL Server Test (Powered by Qualys SSL Labs)
Our site (office.getjoan.com) has a DNS through Cloudflare and it is set as a CNAME (joan-office.netlify.app) with TTL 5min