Hello,
I am thinking about my old smartphone. If voice is very low during typical phone calls but it improves when I go on loudspeaker, do you think it could be more device issue or os issue? It was not like that before. I thought that my device aged too quickly 
The second thing is that this phone stopped giving Hotspot, which was not an issue earlier.
I am not sure if it is better to invest in repairing this specific phone or it would be better to buy a new one. Unfortunately I am not that technical to choose
Regain your privacy! Adopt /e/ the unGoogled mobile OS and online services