Glicko-2 rating system: are there any factors that change the value of a rating?

is the value (chess skill) of a certain rating (i.e. 1800) within a certain time control (i.e. Rapid) always worth the same over time, or are there factors that influence the value of a rating value (i.e. the number of players within the rating pool)?

Why this question is important to me: If we assume that there are factors that significantly influence the value of a certain rating over time, then comparisons between our current and past ratings may be less accurate.

Of cource it will drift one direction or a another, since there are various thing that make Glicko non-zero-sum it has potential of drift even on stable situation. And people (young usually) may gain strength vey quicly and pulling points away from pool.

Not significantly though so you can safely compare ratings few years apart. Dunno if someone has made simulations on the drift?

The chess skill of a certain rating depends *mainly* on the chess skills of all the other players that have played recently in the system.