My best guess is either Bot Fight Mode or Browser Integrity Check feature challenges or blocks the request
You should see the challenged/blocked firewall events in the firewall events if you navigate to the Cloudflare dashboard → Security → Overview and lookup for Firewall events for the past 24hours or so. Once you find them, click on a particular one to find more details about it (user-agent, IP, HTTP version …).
Could you share some details which service was triggered that blocked you?
You could determine if this behaviour continues even by using a “Pause” option at Cloudflare as follows:
Use the “Pause Cloudflare on Site” option from the Overview tab for your domain at dash.cloudflare.com .
The link is in the lower right corner of that page.
Give it five minutes to take effect, then make sure site is working as expected with HTTPS.
Re-try with updating.
Upon success, un-pause and continue using Cloudflare.