Error when saving changes in DNS Zone Editor

One of our customers is getting errors when trying to save changes in the DNS zone editor.  It tries for about 10 seconds, then shows a vague "Something went wrong" message in the top right corner of the screen, although the changes do get written to the zone file in /var/named.

The CWP error log repeats the following a few times:
2024/07/12 13:05:44 [notice] 627729#0: *8207 "^/v1/([^/]+)/?$" matches "/v1/sendComv2", client: 127.0.0.1, server: localhost, request: "POST /v1/sendComv2 HTTP/1.1", host: "127.0.0.1:2302"
2024/07/12 13:05:44 [notice] 627729#0: *8207 rewritten data: "/v1/index.php", args: "method=", client: 127.0.0.1, server: localhost, request: "POST /v1/sendComv2 HTTP/1.1", host: "127.0.0.1:2302"
2024/07/12 13:05:44 [info] 627729#0: *8207 client 127.0.0.1 closed keepalive connection
2024/07/12 13:05:44 [notice] 627729#0: *8209 "^/v1/([^/]+)/?$" matches "/v1/sendComv2", client: 127.0.0.1, server: localhost, request: "POST /v1/sendComv2 HTTP/1.1", host: "127.0.0.1:2302"
2024/07/12 13:05:44 [notice] 627729#0: *8209 rewritten data: "/v1/index.php", args: "method=", client: 127.0.0.1, server: localhost, request: "POST /v1/sendComv2 HTTP/1.1", host: "127.0.0.1:2302"
2024/07/12 13:05:44 [info] 627729#0: *8209 client 127.0.0.1 closed keepalive connection

Then once the error is shown on screen, the log shows this:
2024/07/12 13:05:46 [error] 627729#0: *8109 FastCGI sent in stderr: "PHP message: PHP Warning:  addslashes() expects exactly 1 parameter, 2 given in /usr/local/cwpsrv/var/services/user_files/modules/dns_zone_editor.php on line 0
PHP message: PHP Notice:  Undefined variable: [obfuscated] in /usr/local/cwpsrv/var/services/user_files/modules/dns_zone_editor.php on line 0" while reading response header from upstream, client: x.x.x.x, server: localhost, request: "POST /cwp_x/x/x/index.php?module=dns_zone_editor&acc=editdnsrecord HTTP/1.1", upstream: "fastcgi://unix:/usr/local/cwp/php71/var/sockets/x.sock:", host: "vps####.x.com:2083", referrer: "https://vps####.x.com:2083/cwp_x/x/?module=dns_zone_editor"

Since the PHP script named in the error is encoded, I can't even see where the error is actually occurring. Does anyone have any idea how to fix this?

If you look, something is trying to access port 2302 on the localhost IP.

Which is a port DNS or CWP doesn't use, and really neither does anything else.

Are they trying to use CWP as the PRI or SEC DNS?