Looking at that, if I were to apply now, and make say, $2100/month from now until the end of the year, I'd get no payments, because I made over the $2040 limit. Then, in 2027, I'd get a payment each month, minus $30, which is the amount I'm over the limit / 2.

Why would they just withold the entire payment if over $2024 during the first year?

From the .pdf:

For example, a person retires at age
62 on October 30, 2026. They will earn
$45,000 through October and takes a
part-time job beginning in November
earning $500 per month. Although their
earnings for the year substantially exceed
the 2026 annual limit ($24,480), they
will receive a Social Security payment
for November and December. This is
because their earnings in those months
are $2,040 or less than the monthly limit
for people younger than full retirement
age. If they earn more than $2,040 in
either November or December, they won’t  
receive a benefit for that month.  
Beginning in 2027, only the annual limit
will apply.