Native http request waits infinity for no apparent reason

I have a problem with http calls. I use this plugin to prevent CORS issues when I’m on device. I initiate a series of POST calls which return zips to me. The first 11 work without problems. The 12th remains blocked for several minutes (even if the remote service always responds in 30 seconds), until it times out (even if I increase the timeout to 10 minutes, for example, it remains there). On the server side the logs tell me that the response ended in about 30 seconds as always, on the mobile side the call does not end.
I use Ionic v 6.20.3 with capacitor (v 3)
Can you give me some reason?
Thank you