One of the observations that supports the Big Bang theory is the redshift of galaxies. If the universe were static then the light that we observe would not be so redshifted (the wavelength of light gets stretched out making it more red). However, that doesn’t mean that galaxies are moving away from us, just that there is comic expansion puts greater distance between things.
From The Latest Webb Observations Don’t Disprove The Big Bang, But They Are Interesting.
See also:
- Might there one day be a Big Crunch?
- The Big Bang doesn’t explain why we don’t see more stuff. An anti-universe could explain dark matter