Bypassing Caps - what is it really about?

https://components101.com/articles/decoupling-capacitor-vs-bypass-capacitors-working-and-applications#:~:text=The%20Bypass%20capacitor%20is%20used,spikes%20on%20the%20supply%20lines.

The main capacitors, or AKA "filter capacitors" in an amplfiier will together with the power transformer(s) influence sound quality overall, but most importantly have great impact on the level of clarity and transient response in fast-paced music; also important for resolving nuanced details in slower tracks.

So I’m not talking about bypass circuits. I’m taking about what hi-fi people call "bypassing a capacitor", which is running two capacitors in parallel, typically using a small value to piggy back the main value.

Larger capacitors act as inductors at AC frequencies. The larger the cap and the higher the frequency, the higher the "resistance" presented by the cap. This can impede or roll off frequency response (impedence). A small value cap across the large value cap allows those frequencies to pass. Kinda like overtaking a slower semi on a small road.