SharePoint list has random write protection for user

Question

We have a SharePoint Online list which automatically sets for ~80% of the users a write protection:

Unfortunately these users should have write or full access to the list.

I already checked item level permission but they inherit it from the list, the list inherits from the SharePoint. What needs to be said is that it has a lot of columns:

Type	Column count
Choice	1
Calculated	12
Single Text	3
Number	144 (really)

Total item count: 87

What bothers me is that it's totally random who can (not) edit items. Although the ability to edit changes from time to time.

Are there some (undocumented) thresholds which need to be considered when creating and using lists?

Answer 1

1.The column limit in SharePoint Online is called Row size limit, this specifies the maximum number of table rows internal to the database used for a list or library item. To accommodate wide lists with many columns, each item is wrapped over several internal table rows, up to 6 rows and up to a total of 8,000 bytes (excluding attachments).

2.Displaying 12 or more columns of the following types can cause a list view threshold error: people, lookup, and managed metadata.

In order to improve the performance of the list, please optimize your list to reduce possible problems such as permissions or views.