Kaido proceed to mop the floor with (Gear) Luffy well before he started getting serious, so no.
Also, It isn't the sole example at all. With Doflamingo was the same, with Katakuri (during the FS learning) was the same, and so on.
Luffy often overperforms in base and then gets trashed or anyway needs far stronger forms to fight enemies he seemed to match in base the chapter before.
And anyway no.
The fact that Imu was seious against Loki what has to do with Luffy being trashed as soon as Imu is as serious as he was against Loki?
If not this is a Base Luffy (who blizted Hybrid Kaido) >>> BM (who matched base Kaido) type of take.