How to run Bleachbit on system-shutdown & restart (UbuntuMate with systemd)

Hi!
I know a similar question has been allready asked in the past. However, the solution did not bring me any success. That's why I'm now writing my specific problem here.

I use a virtual machine with UbuntuMate 20.4 LTS. It uses systemd for the process management. And I use bleachbit 4.2.0

My question:
Is there is a possibility to run bleachbit (using systemd) at shutdown and restart of UbuntuMate20.4?
I think that a script and a * .service file are necessary for this. Unfortunately, I have too little experience with systemd and I don't know what the * .service file and the associated script should look like. Do you have a suggestion for a solution to the problem?
(Or perhaps a completely other solution?)

Kind regards, MichaelJC