It looks like sign bans are usually unconstitutional when content-based, where the substance of what is being communicated is taken into account (e.g. bans on only commercial signs), but generally hold up if content-neutral and based on reasonable factors, such as safety or aesthetics.

See Reed v. Town of Gilbert (content-based ban struck down) versus Scenic Arizona v. City of Phoenix (content-neutral and safety-based ban on electronic signs upheld).

https://www.scenic.org/sign-control/billboard-laws/important...