The significant increase in the size of your PDF file when adding text could be due to the way the PDF is being generated or the specific content being added. When using Microsoft Edge to create or modify PDFs, certain elements like high-resolution images or complex graphics can lead to larger file sizes. Additionally, if the PDF contains a lot of raster data or gradients, this can also contribute to the increased size.
Since you mentioned that it worked fine on your backup computer, it could be helpful to check the settings or configurations on the computer where the issue occurred. Ensure that any print settings or PDF generation options are optimized for smaller file sizes.
If the problem persists, consider using a different PDF editing tool or software that may handle the file size more efficiently.