Weird APT/Buster issues when Checking for updates

Seems like there’s no pubkey. Is this repo important? Maybe I could just delete it

Hit:1 http://ftp.us.debian.org/debian buster InRelease
Hit:2 http://ftp.us.debian.org/debian buster-updates InRelease
Ign:3 http://repo.mongodb.org/apt/debian buster/mongodb-org/4.4 InRelease
Hit:4 https://repo.delellis.com.ar buster InRelease
Hit:5 http://forge.yunohost.org/debian buster InRelease
Hit:6 http://security.debian.org/debian-security buster/updates InRelease
Hit:7 http://repo.mongodb.org/apt/debian buster/mongodb-org/4.4 Release
Err:4 https://repo.delellis.com.ar buster InRelease
  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 39217939ED3D07DB                                                                                           
Get:8 https://download.docker.com/linux/debian buster InRelease [54.0 kB]
Hit:9 https://packages.sury.org/php buster InRelease
Hit:10 https://deb.nodesource.com/node_14.x buster InRelease
Fetched 54.0 kB in 2s (31.4 kB/s)
Reading package lists... Done                                                                                                                                                                                 
W: http://ftp.us.debian.org/debian/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                                      
W: http://ftp.us.debian.org/debian/dists/buster-updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                              
W: https://repo.delellis.com.ar/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                                         
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://repo.delellis.com.ar buster InRelease: The following signa
tures couldn't be verified because the public key is not available: NO_PUBKEY 39217939ED3D07DB                                                                                                                
W: http://forge.yunohost.org/debian/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                                     
W: http://security.debian.org/debian-security/dists/buster/updates/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                   
W: http://repo.mongodb.org/apt/debian/dists/buster/mongodb-org/4.4/Release.gpg: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                 
W: https://packages.sury.org/php/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                                        
W: https://download.docker.com/linux/debian/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                             
W: https://deb.nodesource.com/node_14.x/dists/buster/InRelease: The key(s) in the keyring /etc/apt/trusted.gpg.d/php.gpg are ignored as the file has an unsupported filetype.                                 
W: Failed to fetch https://repo.delellis.com.ar/dists/buster/InRelease  The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 39217939ED3D07DB                     
W: Some index files failed to download. They have been ignored, or old ones used instead.