one observation about this: it seems that the OP switched-off hotspot-mode which let the Wifi active and this in turn is re-connecting to the AP SSID Wehlan;
when I end hotspot-mode in my BQ, I always use "switch-off Wifi" (which switches-off the hotspot too) because I do not want that the BQ connects to an unknown or unwanted AP;
one observation about this: it seems that the OP switched-off hotspot-mode which let the Wifi active and this in turn is re-connecting to the AP SSID Wehlan;
when I end hotspot-mode in my BQ, I always use "switch-off Wifi" (which switches-off the hotspot too) because I do not want that the BQ connects to an unknown or unwanted AP;