I pasted 2 tables into my research notes from an HTML source and it appeared to render correctly at the time.
I saved the project, but this morning when I open the document both tables have changed column widths. I see the last column squashed to a single column width and vastly elongated to fit the text in. The other columns appear equally spaced.
I open the same project on my MacBook, and the formatting is correct. My Mac Scrivener is v3.1.5 (12258). I have attached the (zipped) RTF file to the bug report.