try this :
layer7-bittorrent-exp:
^(\x13bittorrent protocol|azver\x01$|get /scrape?info_hash=get /announce?info_hash=|get /client/bitcomet/|GET /data?fid=)|d1:ad2:id20:|\x08’7P)[RP]
/ip firewall filter
add action=add-src-to-address-list address-list=Torrent-Conn address-list-timeout=2m chain=forward layer7-protocol=layer7-bittorrent-exp src-address=192.168.50.0/24 src-address-list=!allow-bit
add action=drop chain=forward dst-port=!0-1024,8291,5900,5800,3389,14147,5222,59905 protocol=tcp src-address-list=Torrent-Conn
add action=drop chain=forward dst-port=!0-1024,8291,5900,5800,3389,14147,5222,59905 protocol=udp src-address-list=Torrent-Conn