Description

WordPress 5.8. When having more than 25 blocks in a widgets area, including "Inactive widgets", can't save changes. When updating got the error: There was an error. Invalid parameter(s): requests.
In console:

Step-by-step reproduction instructions

1. Go to Appearance > Widgets
2. Add Blocks to a widgets area (e.g. "Footer"), as example 5 blocks. Be sure the number of blocks must be 25 or lower.
3. Click "Update" and changes are correctly saved.
4. Repeat step 2 but be sure you have more than 25 blocks in a single widgets area.
5. Click "Update"

Expected behaviour

The changes must be saved

Actual behaviour

Changes can't be saved

WordPress information

• WordPress version: 5.8
• Gutenberg version: 11.0.0
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? Yes, Twenty Twenty-One

Device information

• Device: Desktop
• Operating system: MacOS Big Sur 11.4
• Browser: Firefox 89.0.2