Private key authentication fails when key path has special characters

[jm-teratek]

When using private key stored in my user folder C:/Users/JanneMäkelä/.ssh/ I get no connection to my ssh server.
If I move the private key to another folder or try it with an user without "ä" in their username, the connection works just fine. Nothing even even appears in the server side auth.log when the connection fails.
Timestamps are off by three hours due to timezone.

sshfs-win-manager log

date: 2025-04-09T06:40:04.952Z
conntype: key-file
cmd: "C:\Program Files\SSHFS-Win\bin\sshfs.exe" [Redacted]:/ F: -p22 -ovolname=Koontivalvomo -odebug -ologlevel=debug1 -oStrictHostKeyChecking=no -oUserKnownHostsFile=/dev/null -oidmap=user -ouid=-1 -ogid=-1 -oumask=000 -ocreate_umask=000 -omax_readahead=1GB -oallow_other -olarge_read -okernel_cache -ofollow_symlinks -oPreferredAuthentications=publickey -oIdentityFile="C:/Users/JanneMäkelä/.ssh/id_rsa"

date: 2025-04-09T06:40:20.691Z
conntype: key-file
cmd: "C:\Program Files\SSHFS-Win\bin\sshfs.exe" [Redacted]:/ F: -p22 -ovolname=Koontivalvomo -odebug -ologlevel=debug1 -oStrictHostKeyChecking=no -oUserKnownHostsFile=/dev/null -oidmap=user -ouid=-1 -ogid=-1 -oumask=000 -ocreate_umask=000 -omax_readahead=1GB -oallow_other -olarge_read -okernel_cache -ofollow_symlinks -oPreferredAuthentications=publickey -oIdentityFile="C:/perkule/id_rsa"

Server side auth.log:
Apr 9 09:38:41 [Redacted] sudo: [my user name] : TTY=pts/0 ; PWD=/var/log ; USER=root ; COMMAND=/usr/bin/tail auth.log -f
Apr 9 09:38:41 [Redacted] sudo: pam_unix(sudo:session): session opened for user root by my user name
Apr 9 09:38:45 [Redacted] sshd[22397]: Connection closed by authenticating user [my user name] [my ip address] port 50527 [preauth]
Apr 9 09:39:01 [Redacted] CRON[22729]: pam_unix(cron:session): session opened for user root by (uid=0)
Apr 9 09:39:01 [Redacted] CRON[22729]: pam_unix(cron:session): session closed for user root
Apr 9 09:40:19 [Redacted] sshd[24300]: Accepted publickey for [my user name] from [my ip address] port 50555 ssh2: RSA SHA256:[Redacted]
Apr 9 09:40:19 [Redacted] sshd[24300]: pam_unix(sshd:session): session opened for user [my user name] by (uid=0)
Apr 9 09:40:19 [Redacted] systemd-logind[589]: New session 248 of user [my user name].
Apr 9 09:40:27 [Redacted] sshd[24360]: Received disconnect from [my ip address] port 50555:11: disconnected by user
Apr 9 09:40:27 [Redacted] sshd[24360]: Disconnected from user [my user name] [my ip address] port 50555
Apr 9 09:40:27 [Redacted] sshd[24300]: pam_unix(sshd:session): session closed for user [my user name]
Apr 9 09:40:27 [Redacted] systemd-logind[589]: Removed session 248.