@Horst-Weyrich
These strange spikes are due to interferences by WiFi sources
Please see this document
These spikes appear when DFS of RLAN-WiFi equipment is not correctly operating :

https://en.m.wikipedia.org/wiki/Dynamic_frequency_selection

https://ams.confex.com/ams/pdfpapers/97361.pdf

https://blog.iptel.com.au/wifi-and-the-problem-with-radar#:~:text=RADAR can interfere with Wi,removing a source of interference.