There is no loss of fidelity, no loss of image quality, and no change in data associated with zipping or unzipping.

Does compression cause quality loss?

Lossy compression formats suffer from generation loss: repeatedly compressing and decompressing the file will cause it to progressively lose quality. This is in contrast with lossless data compression, where data will not be lost via the use of such a procedure.

How do I compress files without losing quality?

6 Ways to Make Video Files Smaller without Losing Quality