When you say "My tor exit node was 188.8.131.52:443", I presume you do not mean that you are the operator of the nicknamed chaoscomputerclub21 Tor node.
I think you mean that the Tor node in use as an exit node, for one or more of your Tor client's open circuits, was at that IP address.
Your Tor client will create multiple circuits at one time, and over time. Any node with Guard and Exit flags (chaoscomputerclub21 has both at the present time) could randomly be used as an entry guard, a middle node, and an exit. It being an exit in one circuit doesn't mean it can't be an entry guard in another, or a middle node in still another.
You should be able to use the tool (arm?) that showed you the chaoscomputerclub21 exit node selected for that one circuit to also see the entry and middle nodes. You can look at multiple circuits in that and probably see more than one instance of any given high capacity node showing up in various roles.