For my Project i use the youtube-player api and i need the Transcript of an Video and Video id's of an playlist

I would like to get the Standard Youtube Transcript, which you get when you click "show transcript" on youtube.com. (either native language or autogenerated if not available)

When you click "show transcript" a request with a signature/key is made to the youtube api

https://www.youtube.com/api/timedtext?v=jn3wG4z_Scw&caps=asr&xoaf=4&hl=de&ip=0.0.0.0&ipbits=0&expire=1654051365&sparams=ip,ipbits,expire,v,caps,xoaf&signature=4D4509AD58E6D34D867B3F2BF4E4B2B808751A3A.48AE333D8C981F804D4320864E2A583C58D5F543&key=yt8&lang=de&fmt=json3&xorb=2&xobt=3&xovt=3

Can i reverse engineer the JS to get the functions which generate the Request. (espacially the key/signature creator) If it's possible are there any tools that help? Maybe i can avoid using an API key with php? Or should i just give in and use the official youtube api?

For some reason i don't want to use an api key. maybe because of scalability, not associating a account with the project, kepping the project as local as possible. feel free to change my mind