This is from the server error log after pressing save.
[Sat Feb 13 16:30:36.538457 2021] [cgi:error] [pid 19206:tid 4107689264896] [client 00.00.00.000:44420] AH01215: PHP Warning: count(): Parameter must be an array or an object that implements Countable in /home/user/MYDOMAIN.org/wp-includes/kses.php on line 895: /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/
[Sat Feb 13 16:30:36.539193 2021] [cgi:error] [pid 19206:tid 4107689264896] [client 00.00.00.000:44420] AH01215: PHP Warning: count(): Parameter must be an array or an object that implements Countable in /home/user/MYDOMAIN.org/wp-includes/kses.php on line 895: /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/
[Sat Feb 13 16:32:11.205786 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: PHP Fatal error: Uncaught Error: Call to undefined function _sanitize_text_fields() in /home/user/MYDOMAIN.org/wp-content/plugins/wp-cerber/common.php:804: /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.205968 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: Stack trace:: /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.206212 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #0 [internal function]: {closure}('1', 'botscomm'): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.206720 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #1 /home/user/MYDOMAIN.org/wp-content/plugins/wp-cerber/common.php(805): array_walk_recursive(Array, Object(Closure)): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.207210 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #2 /home/user/MYDOMAIN.org/wp-content/plugins/wp-cerber/admin/cerber-settings.php(1118): crb_sanitize_deep(Array): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.207692 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #3 /home/user/MYDOMAIN.org/wp-content/plugins/wp-cerber/admin/cerber-settings.php(74): cerber_settings_update(): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.208185 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #4 /home/user/MYDOMAIN.org/wp-content/plugins/wp-cerber/admin/cerber-settings.php(42): cerber_admin_init(): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.208505 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #5 /home/user/MYDOMAIN.org/wp-includes/plugin.php(524): {closure}(''): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.208881 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #6 /home/user/MYDOMAIN.org/wp-admin/admin.php(154): do_action('admin_init'): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.209283 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #7 /home/user/MYDOMAIN.org/wp-admin/options.php(19): require_once('/home/user...'): /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.209340 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: #8 {main}: /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha
[Sat Feb 13 16:32:11.209729 2021] [cgi:error] [pid 21370:tid 4108051662592] [client 00.00.00.000:43667] AH01215: thrown in /home/user/MYDOMAIN.org/wp-content/plugins/wp-cerber/common.php on line 804: /dh/cgi-system/php72.cgi, referer: https://www.MYDOMAIN.org/wp-admin/admin.php?page=cerber-recaptcha