@shimekeleme this sounds like your phone is having issues with the headphone jack. That jack is soldered to the daughterboard (charging board). I would suggest that you replace that board and then re-evaluate if it works. If not then the issue could be on the main circuit board.
Since iFixit does not yet have a specific guide for this, use the one [https://www.nadiemellamagallina.com/en/manuales/smartphones-1/samsung-4/samsung-galaxy-a70-1084/placa-auxiliar-9482|from here] It is written in Spanish so use a browser that will do the translating for you, if needed. Replacement boards are readily available at many online stores.
While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.
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