The error you're encountering, "The phone verification request contains an invalid application verifier," can sometimes occur due to invalid or unsupported phone numbers. I ran into a similar issue while working on phone number authentication with Firebase, and I found that this error often happens when numbers aren’t fully validated or don’t meet the required standards.

One trick that worked wonders for me was ensuring the phone numbers I was using were properly validated before sending them to Firebase. I started checking the numbers for proper formatting (like E.164 format) and making sure they were actually mobile numbers. I used a phone number validation tool Landline remover that helped me filter out landlines and VoIP numbers, which don’t work well with Firebase authentication.

By adding this validation step, I reduced the number of reCAPTCHA token issues significantly. The numbers that went through were always the right ones, making the process smoother and more reliable.

you should try phone number validation tool " https://landlineremover.com/api/ "may that help you!