I noticed that sometime when I download the key/pem files that there is an extra blank line between the end of the key and the "-----END RSA PRIVATE KEY-----".

like so:
...

BqqxIKzjl3fRW0abj1dUcj33/lsJuWDTWreWa7dIPAwPG0fQfkABqfpU/v5E/CAA
1j1EYyis7o+P4fS/KpZis8NlzIb4TXwpigqt/Uhr27l1Xrko79EcPtrRk21fswAs
m9pd44zpjCKMHAID2spXirE6Y+RX4sduIpVURwdxWw/9sKEGRZJifP/LULrLZw==

-----END RSA PRIVATE KEY-----

This blank line causes the key to be invalid in some apps I use.

I'm not sure if the blankline is coming from certwarden or perhaps let's encrypt.

I added a a line to my post-processing scripts to remove blank lines from the key/pem files so it's not a big deal but wanted you to be aware if you weren't

Also it's hard to see in this post since I didn't find a fixed-width font but I think it only happens when the last line is the exactly 64 characters

Thanks
Frank.