Coś bardzo Ciekawego :)

command /kupka:    trigger:        loop all players:            set {_} to 19            loop 20 times:                if {_} is 1:                    display "Koniec czasu!" on bossbar with 100 percent by 59 seconds for loop-player                stop                display "%{_}% minut" on bossbar with 100 percent by 59 seconds for loop-player                add -1 to {_}                wait 1 minute

command /kupka:    trigger:        loop all players:            set {_} to 19            loop 20 times:                if {_} is 1:                    display "Koniec czasu!" on bossbar with 100 percent by 59 seconds for loop-player                stop                display "%{_}% minut" on bossbar with 100 percent by 59 seconds for loop-player                add -1 to {_}                wait 1 minute

Przed stop potrzeba jeszcze jednego taba.

Ogey, poprawie za niego ;_;

command /kupka:    trigger:        loop all players:            set {_} to 19            loop 20 times:                if {_} is 1:                    display "Koniec czasu!" on bossbar with 100 percent by 59 seconds for loop-player                    stop                display "%{_}% minut" on bossbar with 100 percent by 59 seconds for loop-player                add -1 to {_}                wait 1 minute

działa dzięki do zamknięcia