Gaussian Filter with sigma = 1 pixel:

Gaussian Filter with sigma = 2 pixel:

Gaussian Filter with sigma = 3 pixel:

Lee Additive Noise filter:

Lee Multiplied Noise filter:

Lee A&M Noise filter:

The original signal is about 4~5 sigma, it should be detected by a 3 sigma clip threshold.

but the gaussian filter with sigma = 2 pixel, blur the signal and make the peak lower than 3 sigma of background noise.

Lee's filter might not suppress noise as well as Gaussian filter, but it won't affect the profile (or shape) of signal that much.