DNS Errors Occurred (Reverse DNS) even if PTR is shown by "host" command

Ticket: [COLOR=rgb(184, 49, 47)]93574906 . Following problem applies to ALL accounts under WHM, even if server's main IP is resolved as reversed. Although no problem with AutoSSL. My Provider has already set IP to resolve to the hostname I use, in case it helps. Nevertheless, by host command, seems that Main IP does look like it has rDNS with no problem. host 185.4.xxx.xxx xxxx.xxx.4.185.in-addr.arpa domain name pointer my.hostname.com.
Every cPanel account WHM > Email " Email Deliverability Further information dig txt default._domainkey.my.hostname.com. ; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> txt default._domainkey.my.hostname.com. ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 10537 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;default._domainkey.my.hostname.com. IN TXT ;; ANSWER SECTION: default._domainkey.my.hostname.com. 14399 IN TXT "v=DKIM1; k=rsa; p=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx;" ;; Query time: 89 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Sun Aug 09 23:59:01 EEST 2020 ;; MSG SIZE rcvd: 494
dig -x 185.4.xxx.xxx ; <<>> DiG 9.11.4-P2-RedHat-9.11.4-16.P2.el7_8.6 <<>> -x 185.4.xxx.xxx ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3616 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;xxx.xxx.4.185.in-addr.arpa. IN PTR ;; ANSWER SECTION: xxx.xxx.4.185.in-addr.arpa. 21599 IN PTR my.hostname.com. ;; Query time: 54 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Mon Aug 10 00:09:18 EEST 2020 ;; MSG SIZE rcvd: 90 [/code[ for i in {a..m}; do echo -n "$i.root-servers.net: "; dig -4 "$i".root-servers.net @"$i".root-servers.net +short;done a.root-servers.net: 198.41.0.4 b.root-servers.net: 199.9.14.201 c.root-servers.net: 192.33.4.12 d.root-servers.net: 199.7.91.13 e.root-servers.net: 192.203.230.10 f.root-servers.net: 192.5.5.241 g.root-servers.net: 192.112.36.4 h.root-servers.net: 198.97.190.53 i.root-servers.net: 192.36.148.17 j.root-servers.net: 192.58.128.30 k.root-servers.net: 193.0.14.129 l.root-servers.net: 199.7.83.42 m.root-servers.net: 202.12.27.33
nslookup 185.4.xxx.xxx Name: my.hostname.com Address: 185.4.xxx.xxx