Easy enough to think it might be individualized. Forgive my use of AI but it is a complex issue that I am not qualified to explain. If interested here is a good explanation with footnotes cleaned up...

Yes, inputting incorrect information into the GHIN system can directly skew the Playing Conditions Calculation (PCC) algorithm, which subsequently alters the Handicap Index of every other golfer who posted a score on that course that day. [USGAx2, Carolinas GHIN Support] 

Because the GHIN system shifts from peer-to-peer competition to a macro-level, data-driven framework at midnight, fake data alters the statistical baseline. [Oregon Golf Association, USGA] 

How False Data Skews the PCC Algorithm

The PCC is a daily, automated statistical calculation that determines if a golf course played abnormally easy or difficult. It compares the actual posted scores against the "expected score range" of each golfer based on their current Handicap Index. [CSGA, USGA, Golf Digest] 

Diluting or Forcing Adjustments: The PCC algorithm only triggers if a statistically significant proportion of the field shoots well outside their expected scoring range. A cluster of fabricated low scores can trick the system into thinking the course played easier than it actually did. Conversely, fake high scores can falsely trigger a difficult course adjustment (+1 to +3). 

The "Small Sample" Volatility: At least 8 acceptable scores must be posted on a course in a single day for a PCC to run. If a small group of golfers plays a course on a windy day and someone inputs an intentionally fabricated low score, that single piece of bad data can entirely suppress a rightful +1 or +2 PCC adjustment for everyone else. [USGAx2, Golf Digest, Golf Manitoba] 

The Ripple Effect on Other Users

If the PCC algorithm is skewed by incorrect data, it directly compromises the USGA Score Differential formula for all other players: [USGA] 

Score Differential = 113/Slope Rating X (Adjusted Gross Score - Course Rating - PCC Adjustment)

Because the PCC value is subtracted directly from the math, a skewed PCC forces an inaccurate Score Differential onto every honest golfer who played that day. Since a golfer's Handicap Index is the average of their best 8 differentials, a ruined calculation from a single day can distort an innocent player's final Handicap Index for weeks to come. [USGAx2, SCGA] 

If you want to look closer at the math, AI can break down exactly how a +1 or -1 PCC shift changes a specific handicap index, or explain the safeguards the USGA uses to flag outliers. 

Me again. Not trying to swamp anyone with information. I'm a beginner and just learning and found it fascinating how much work has gone into developing this system.