DNS-over-HTTPS not working(?)

It seems that dns-over-https is not working.
(PiHole is running on Ubuntu server 18.04 VM)

I followed these guides:

https://docs.pi-hole.net/guides/dns/cloudflared/

I got this result:

dig @127.0.0.1 -p 5053 google.com

; <<>> DiG 9.11.3-1ubuntu1.15-Ubuntu <<>> @127.0.0.1 -p 5053 google.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 13785
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 670f583a6b5167f3 (echoed)
;; QUESTION SECTION:
;google.com.                    IN      A

;; ANSWER SECTION:
google.com.             90      IN      A       142.250.185.78

;; Query time: 0 msec
;; SERVER: 127.0.0.1#5053(127.0.0.1)
;; WHEN: Tue Oct 12 18:38:41 UTC 2021
;; MSG SIZE  rcvd: 77

https://1.1.1.1/help#eyJpc0NmIjoiTm8iLCJpc0RvdCI6Ik5vIn0=

It is working now. I had taken a snapshot of the vm just before installing cloudflared, so I reverted and installed the doh service again and it's working.

Something else that concerns me it is that https://1.1.1.1/help sometimes shows "Using DNS over HTTPS (DoH) - NO"
Then I restart the service and it is working again. A couple of times I had to reboot the vm to make it work.
Any idea why is this happening?

Please generate a debug log, upload it when prompted and post the token URL here.

Will you help me to generate the log, please?

The first attempt testing with https://1.1.1.1/help showed that DoH was not in use.
I refreshed the page and it showed that it was in use.

Here it is:
https://tricorder.pi-hole.net/o8D5YId8/

I cannot understand why is this happening after some time.

● cloudflared.service - cloudflared DNS over HTTPS proxy
   Loaded: loaded (/etc/systemd/system/cloudflared.service; enabled; vendor preset: enabled)
   Active: active (running) since Sat 2021-10-16 12:13:09 EEST; 7h ago
 Main PID: 967 (cloudflared)
    Tasks: 6 (limit: 1077)
   CGroup: /system.slice/cloudflared.service
           └─967 /usr/local/bin/cloudflared proxy-dns --port 5053 --upstream https://1.1.1.1/dns-query --upstream https:

Oct 16 19:50:33 pihole cloudflared[967]: 2021-10-16T16:50:33Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:34 pihole cloudflared[967]: 2021-10-16T16:50:34Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:36 pihole cloudflared[967]: 2021-10-16T16:50:36Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:37 pihole cloudflared[967]: 2021-10-16T16:50:37Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:37 pihole cloudflared[967]: 2021-10-16T16:50:37Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:38 pihole cloudflared[967]: 2021-10-16T16:50:38Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:38 pihole cloudflared[967]: 2021-10-16T16:50:38Z ERR failed to connect to an HTTPS backend "https://1.0.0.1
Oct 16 19:50:38 pihole cloudflared[967]: 2021-10-16T16:50:38Z ERR failed to connect to an HTTPS backend "https://1.0.0.1
Oct 16 19:50:40 pihole cloudflared[967]: 2021-10-16T16:50:40Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
Oct 16 19:50:40 pihole cloudflared[967]: 2021-10-16T16:50:40Z ERR failed to connect to an HTTPS backend "https://1.1.1.1
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