Unexpected jump in request count between c=149 and c=150 about autocannon HOT 2 CLOSED

wrk -t30 -c130 -d20s https://localhost
Running 20s test @ https://localhost
  30 threads and 130 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    79.52ms    8.92ms 131.95ms   78.31%
    Req/Sec    50.09     13.83   120.00     80.56%
  30018 requests in 20.04s, 15.25MB read
  Non-2xx or 3xx responses: 10
Requests/sec:   1497.63
Transfer/sec:    779.32KB

wrk -t30 -c140 -d20s https://localhost
Running 20s test @ https://localhost
  30 threads and 140 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    79.14ms    8.74ms 134.93ms   81.51%
    Req/Sec    50.36     14.97    80.00     77.87%
  30178 requests in 20.10s, 15.34MB read
Requests/sec:   1501.34
Transfer/sec:    781.46KB

wrk -t30 -c150 -d20s https://localhost
Running 20s test @ https://localhost
  30 threads and 150 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    24.01ms   36.07ms 366.72ms   82.27%
    Req/Sec     1.00k   383.83     2.61k    69.53%
  594900 requests in 20.06s, 63.99MB read
  Non-2xx or 3xx responses: 576002
Requests/sec:  29653.51
Transfer/sec:      3.19MB