whoami: bad uid 0 / Magisk vs. Toybox

I replaced old /system/bin/toybox with a new binary from [http://landley.net/toybox/bin](http://landley.net/toybox/bin) then I created symlinks with for i in $(./toybox); do ln -s toybox $i. There is su in symlinks. Now I cannot open Magisk anymore, stuck at splash screen mask. Also MiXplorer cannot browse root dirs. With Terminal Emulator I can still browse root dirs. If I type which su I get /sbin/su which is a symlink to /sbin/magisk. I have not yet tried to reboot because I fear to get stuck, maybe it would repair by itself but who knows? If I type whoami I get bad uid 0, after su shell I get bad uid 2000 and so on. How can I restore root? I can access TWRP recovery.