Can TV antenna be used as Radio Antenna?
You have a radio that receives medium wavelength (AM broadcast), short wavelength (shortwave), as well as FM broadcast.
The span of frequencies covered is very wide. An optimum antenna for the bottom end of the AM broadcast band might be 130 metres long, while an optimum antenna for top-of-FM broadcast band might be 0.7 metres long. Although your telescoping antenna can have its length varied, it telescopes mostly to allow convenient storage while not in use. And it certainly cannot be extended to 130 m.
The short antenna provided is far too short for some of the available tuning range of your radio, so the manufacturer has likely included additional internal components to improve its efficiency. They expect that the radio antenna will be used "as is". For the lower frequencies, a ferrite-rod component mounted inside the radio provides much of the signal.

Your telescoping external antenna is likely coupled into this component to provide reasonable coverage (not optimum) of the entire span of receivable frequencies. Attaching external long antennas to the telescoping antenna likely disturbs the coupling, resulting in less-than-optimum signal power.
High performance radios have no internal antenna, and expect the user to provide signal power at a constant resistance (often 50 ohms) to a coaxial connector. Your "consumer" radio is not of this class, but it is more convenient to use.