:local vpnIP [/ip address get [find interface="vpn_Interface"] address];
/ip firewall address-list add list="MY NETWORK" address=$vpnIP;
/ip firewall address-list remove [/ip firewall address-list find list="MY NETWORK" address=$vpnIP];

:local vpnIP [/ip address get [find interface="vpn_Interface"] address];
Will Return Value 10.50.1.1/32

/ip firewall address-list add list="MY NETWORK" address=$vpnIP;
Will Save to address_list 10.50.1.1

/ip firewall address-list remove [/ip firewall address-list find list="MY NETWORK" address=$vpnIP];
This Syntaks Will Find 10.50.1.1/32 and the result not found because in the address List just 10.50.1.1 not 10.50.1.1/32

ros code

:local vpnIP [/ip address get [find interface="vpn_Interface"] address]; :for i from=( [:len $vpnIP] - 1) to=0 do={:if ( [:pick $vpnIP $i] = "/") do={:set vpnIP [:pick $vpnIP 0 $i]}};
/ip firewall address-list add list="MY NETWORK" address=$vpnIP;
/ip firewall address-list remove [/ip firewall address-list find list="MY NETWORK" address=$vpnIP];

ros code

:local vpnIP [/ip address get [find interface="vpn_Interface"] address]; :for i from=( [:len $vpnIP] - 1) to=0 do={:if ( [:pick $vpnIP $i] = "/") do={:set vpnIP [:pick $vpnIP 0 $i]}};
/ip firewall address-list add list="MY NETWORK" address=$vpnIP;
/ip firewall address-list remove [/ip firewall address-list find list="MY NETWORK" address=$vpnIP];