Not Correct log Sweep signal created.

I was trying to generate a logarithmic sweep (log sweep) signal. Specifically, I wanted to create a log sweep starting at 50 Hz and sweeping up to 15 kHz over 5 seconds, while maintaining a constant signal level of 0 dBFS from start to end.

Of course, I set up a 48 kHz sample rate with 32-bit float. However, when I check the generated file, the sweep clearly exceeds the intended 15 kHz limit and continues all the way up to nearly 20 kHz. Additionally, once it goes beyond 20 kHz, the level drops by about 3 dB and the signal continues at that reduced amplitude.

This issue doesn’t occur in other audio editing programs. I also tested it with Python code, and there were no such problems. So I’m wondering — why does this only happen in Adobe Audition?