I always use Master PDF Editor.  The 4.x version is still free to use for linux (funny, linux was always free, but made windoze/mac folks pay, because they obviously have the cash), but 5.0 and on demands cash tax for all.  At least under arch they keep both packages for use.  This has been my go-to pdf editor for 5+ years at least, often using to add a signature or various field inputs to avoid a print, sign, and re-scan type scenario.

I think even at cost it's like $75 bucks, which is still far better than buying adobe acrobat pro malware for $500 bucks to be infected invariably.  I've been using master pdf editor so long I should probably pay them out of respect.

$ yay master pdf
2 aur/masterpdfeditor-free 4.3.89-1 (+56 4.48%) (Installed)
    A complete solution for creation and editing PDF files - Free version without watermark
1 aur/masterpdfeditor 5.6.80-1 (+169 3.69%)
    A complete solution for viewing, creating and editing PDF files

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