DNS not resolving. Lots of FTL errors

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I dont see any servers that could create a loop or a partial one.

Yes.
Check below " Improve detection algorithm ..." paragraph for which server(s) Pi-hole will prefer :

But before you remove the others, make sure Unbound is functioning properly by running below ones:

$ dig +noall +comments +answer @127.0.0.1 -p 5335 bogus.nlnetlabs.nl
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 5007
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232

$ dig +noall +comments +answer +ad @127.0.0.1 -p 5335 cloudflare.com
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59669
;; flags: qr rd ra ad; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; ANSWER SECTION:
cloudflare.com.         300     IN      A       104.16.132.229
cloudflare.com.         300     IN      A       104.16.133.229

The first command should return a SERVFAIL status and no IP address ANSWER.
The second should return a NOERROR status plus an IP address in the ANSWER section in addition to an ad flag.

Ps. those dig's are from below pull to adjust the ones in the official Pi-hole guide: