Currently, some Steam users use third-party services or extensions to track prices, but this may soon change.
SigaTbh drew the community's attention to traces in the code that indicate that Valve is preparing a new feature for tracking game prices:
It seems that Valve intends to implement the ability to track recent game prices on Steam — within 30 days. Something similar already exists in the European Union due to local legislation.
It is not yet clear at what stage the function is in development and when it may be included in the beta version of Steam for public testing.