I've noticed occasionally on winbox the Tx counter for an L2TP tunnel is displaying completely impossible numbers, this also shows in the Traffic tab.
For instance when hosting a session on The game Cosmoteer (Starship architect and commander) and it sends the save file to the other player(s) Winbox will try and tell me I'm sending over 80Mbit/s over the L2TP tunnel for several seconds, this is impossible as the underlying WAN link it's transverses doesn't have 80Mbit/s of upstream bandwidth.
The Tunnel is usually either going over either Starlink or a 30/5 VDSL.
Also with a short keepalive timeout set it seems to lose enough LCP echo's to drop the tunnel entirely.