Why did countries that adopted the Gregorian calendar later have to skip more days?

Countries that adopted the Gregorian calendar later had to skip more days because the Julian calendar, which they were still using, continued to drift out of alignment with the solar year.12

The Julian calendar overestimated the length of the solar year by approximately 11 minutes and 14 seconds. This small discrepancy accumulated over time, causing the calendar to drift by about one day every 128 years. Because the Gregorian reform was not adopted globally at the same time, the gap between the two systems continued to widen as the centuries passed.3241

When Pope Gregory XIII introduced the reform in 1582, he mandated skipping 10 days to correct the accumulated error since 325 CE. Countries that switched to the Gregorian system in later centuries had to drop an even larger number of days to account for the additional drift that had occurred since 1582. For example, Great Britain dropped 11 days in 1752, while Greece dropped 13 days in 1923.13