Hi @S__Z ,
Yes, the limit of the character number in the URL column is 255 in SharePoint Online. This behavior is by design. As a workaround, you could create a Multiple lines of text column to solve this problem.
1.Create Multiple lines of text column.
Add column > Multiple lines of text > More options > Use enhanced rich text (Rich text with pictures, tables, and hyperlinks)
2.Edit Multiple lines of text column.
Edit item > select Multiple lines of text column then click "Edit"
3.Add Hyperlink.
Click ellipsis > click "Add or edit hyperlink"
4.Insert link.
Type your URL link and type display text.
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