There is lots of circumstantial evidence.
1. The Wuhan lab collects bat viruses, and the pandemic started in Wuhan. Coincidence??
2. Three workers at Wuhan lab became sick with a flu-like illness and sought hospital care in November 2019. Their symptoms were consistent with both COVID-19 and common seasonal illness. Link:
https://www.webmd.com/lung/news/20210524/wuhan-lab-researchers-illness
3. And last but not least, China wont allow the WHO into Wuhan lab to do an investigation. What do they have to hide??!!
Thats enough for any rational person to have reasonable suspicion this virus may have escaped from a lab