If you're trying to fill out fillable .PDF forms – like the ones from the U.S. Internal Revenue Service, or many U.S. States – you might want (or need) to use Adobe Reader instead of the built-in Preview application.
I'm using old versions of Preview and of Adobe Reader – and Preview is definitely better for filling out the fillable forms. For instance, I recently filled out a .PDF form that automatically totals certain fields. That works in Adobe Reader. If I edit the file AT ALL in Preview, the auto-totaling breaks. So even though I use Preview for viewing or printing many .PDF files, there are certain .PDF files for which I intentionally avoid using Preview at all.
Maybe things have changed and the version of Preview in Monterey is a lot better at handling fillable forms.
Note that when I fill out these forms, I download (Save) them from a Web browser to my Mac first, and then edit them by opening them from the Adobe Reader application (or dragging their icons onto its Dock icon).