filtering feature table


I am analyzing v3-v5 region of 16S rRNA. while filtering my feature table for mit/chl contaminants I found no difference between table before and after filtering. that clearly suggests that there were no mit/chl DNA sequences.

After that I picked up V3-V4 region from the same dataset, and there I found the difference in feature table. before filtering number of features were 15025 and after it reduced to 15014.
Is it possible that in v3-v5, there were no contaminants detected and v3-v4 I got few?
if yes! how?