Does anyone else have a laggy mouse when connecting the mouse normally via the bluetooth settings? It used to work fine for me until some updates a while ago. Now I have to use the Logitech Unifying Receiver which is annoying. Under Fedora Gnome this did not happen, only under the most recent Ubuntu and Debian 10 stable.
I had the same problem,
following this answer instruction worked for me:
sudo nano /var/lib/bluetooth/xx\:xx\:xx\:xx\:xx\:xx/yy\:yy\:yy\:yy\:yy\:yy/info
where xx:xx.... is pc bluetooth address and yy:yy... is the mouse bluetooth address.
In the file, add this section at the end:
[ConnectionParameters] MinInterval=6 MaxInterval=7 Latency=0 Timeout=216
then, restart bluetooth service with:
systemctl restart bluetooth