The bug
MC-70127 was marked as fixed for 1.20.2 pre-release 1. However, saplings are still seemingly affected by the issue.
How to reproduce
Open your F3 screen
Run the command
/gamerule randomTickSpeed 100
Place a sapling (a single dark oak sapling will not grow but still changes its "state" value making it ideal for this test), paying attention to the right hand side of the screen where it lists block states
Wait five seconds
Right click the sapling
If "state" does not change from 0 to 1, repeat steps 4-5
Expected results
The stage state of the sapling would increase on its own, which would be reported by the debug screen since you're looking at it and right clicking on the sapling wouldn't do anything.
Actual results
Right clicking the sapling causes the displayed "stage" value to instantly increase from 0 to 1, implying that the block's state change on the server was not communicated to the client until a player interaction with this block forced it to update client-side.
Related issues
Comments

Can confirm in 1.20.3 Release Candidate 1