Thank you for the answer:
apt install libevent-2.1-7
dpkg --install check-mk-enterprise-2.0.0p17_0.bullseye_amd64.deb
worked for me 
Now I have the bullseye version installed and it seems that I haven’t the perl issues anymore.
Thank you for the answer:
apt install libevent-2.1-7
dpkg --install check-mk-enterprise-2.0.0p17_0.bullseye_amd64.deb
worked for me Now I have the bullseye version installed and it seems that I haven’t the perl issues anymore.