There's a chance I'm misunderstanding this, but setting the fetch-depth to 2 will cause a comparison of only the last 2 commits on deploy. If you have made more than 2 commits since the last deployment the comparison fails and all files are uploaded again. With even relatively small projects this could make the deployment time go up significantly.
Setting the fetch-depth to 0 will cause it to look back over all commits to determine the delta of files to upload and reduce the FTP time significantly over uploading from scratch. See https://github.com/SamKirkland/FTP-Deploy-Action/issues/82 and possibly https://github.com/SamKirkland/FTP-Deploy-Action/issues/78
Also see the docs related to fetch-depth: https://github.com/actions/checkout#checkout-v2
Complete rewrite!
Switched from LFTP to git-ftp
Upload diffs based on git history by default
lower case kebab argument names
Migrated from shell to typescript
Added FTP and SFTP tests
.git-ftp-ignore and .git-ftp-include support
I found the temporary workaround you mentioned in this issue to be very beneficial, so I am proposing that it be added to the table of flags. I do also see the argument for not including it though, so this is more to open the discussion.