• Significant code improvements and rewrites
• Added support for 1.20.1, 1.21.1, 1.21.9-10, and 1.21.11
• Added waterlogging and rotation for Umbrella Stands
• Umbrellas now visually block rain
• Changed conditions for players' arms raising while holding umbrellas
• Fixed desync when Hoppers interact with Umbrella Stands

There may be issues with updating as a large number of changes have been made. You may need to use creative mode to restore broken items.