If you want to slow down the light LED fireworks of your Raspberry, you can permanently switch off the red and green LEDs on the Raspberry Pi 5. To do this, the config.txt under /boot/firmware must be edited. This can be done with the text editor nano, for example:
sudo nano /boot/firmware/config.txt
Then add the following lines to the end of the file, save and reboot the Raspberry using sudo reboot:
dtparam=pwr_led_trigger=default-on dtparam=pwr_led_activelow=off dtparam=act_led_trigger=none dtparam=act_led_activelow=off dtparam=eth_led0=4 dtparam=eth_led1=4