Let's take a look at the corresponding lines in your debug log:
*** [ DIAGNOSING ]: Operating system
[i] Distro: Debian
[i] Version: 12
[✗] dig IPv4 return code: 9
[✗] dig response: ;; communications error to 205.251.193.151#53: timed out
[i] Retrying via IPv6
[✗] dig IPv6 return code: 9
[✗] dig response: ;; communications error to 2600:9000:5301:9700::1#53: timed out
[✗] Error: dig command failed - Unable to check OS
The OS check failed as communication with the public DNS server for pi-hole.net timed out.
I addition, Pi-hole's debug script also failed to retrieve DNS replies from public DNS servers:
*** [ DIAGNOSING ]: Name resolution (IPv4) using a random blocked domain and a known ad-serving domain
[✓] adf.shinobi.jp is NOERROR on lo (127.0.0.1)
[✓] adf.shinobi.jp is NOERROR on eth0 (192.168.1.137)
[✓] adf.shinobi.jp is NOERROR on br-775f80ffb4cf (172.18.0.1)
[✓] adf.shinobi.jp is NOERROR on docker0 (172.17.0.1)
[✗] Failed to resolve doubleclick.com via a remote, public DNS server (8.8.8.8)
*** [ DIAGNOSING ]: Name resolution (IPv6) using a random blocked domain and a known ad-serving domain
[✓] www.allegrolokalnie.pl-oferta7224283.cfd is NOERROR on lo (::1)
[✓] www.allegrolokalnie.pl-oferta7224283.cfd is NOERROR on eth0 (2001:<redacted>e)
[✓] www.allegrolokalnie.pl-oferta7224283.cfd is NOERROR on eth0 (fe80::d<redacted>4%eth0)
[✓] www.allegrolokalnie.pl-oferta7224283.cfd is NOERROR on br-775f80ffb4cf (fe80::c<redacted>f%br-775f80ffb4cf)
[✓] www.allegrolokalnie.pl-oferta7224283.cfd is NOERROR on docker0 (fe80::f<redacted>7%docker0)
[✗] Failed to resolve doubleclick.com via a remote, public DNS server (2001:4860:4860::8888)
This may suggest that something is blocking DNS requests to public DNS servers for the machine that runs your Pi-hole.
Would your router perhaps only allow specific DNS servers and/or protocols?
Furthermore, there are a few SERVFAIL replies from your upstreams:
Mar 6 00:00:08 dnsmasq[810]: query[AAAA] pool.ntp.org from 192.168.1.137
Mar 6 00:00:08 dnsmasq[810]: forwarded pool.ntp.org to 127.0.0.1#5335
Mar 6 00:00:08 dnsmasq[810]: forwarded pool.ntp.org to 127.0.0.1#5053
Mar 6 00:00:08 dnsmasq[810]: forwarded pool.ntp.org to 1.1.1.1
Mar 6 00:00:08 dnsmasq[810]: reply error is SERVFAIL
As unbound as well as dnscrypt require an accurate time, those SERVFAILs for pool.ntp.org (as required for a time-sync) may indicate that your time is off.
You should verify your Pi-hole machine's time and time zone settings.
And as you are using cloudflared, you should also check Issues with using cloudflared as upstream DNS server.