It's definitely ok to change column widths for different pages.
Why would you keep column widths of cells that aren't in the table anymore and sacrifice readability?
I work on a B2B application that largely consists of tables with pagination and it's definitely not wanted by our customers that column widths don't make sense compared to the contents of the table. See my examples below what I mean.
Using fixed column widths is not a better idea. To find the ultimate width for columns and still make efficiently use of the available space on all pages will be very hard if not impossible. It's better to adapt column widths to their contents and make the table a lot more efficient and useful, this counts for each page.
If comparing columns between pages is needed or highly desirable, pagination might not be the best implementation. Create a filter that users can customize to show only the rows to compare. And/or add options to show more rows on the page or maybe even consider showing the whole table at once.
Page 2 with column widths kept from the previous page
Page 2 with columns widths adapted to the content
With fixed column widths
Getting it right is not easy, maybe even impossible: