This seems to be like a bug as no configuration was changed by me in the middle of the night.
I recall there were similar errors/bug reports in the past were it seemed it was managesieve but wasn't, people had some misconfigurations in the dovecot.conf. I did not change my dovecot.conf since April.
But maybe here it is a pigeonhole issue.

As I did not find any reason for it I changed the repo and downgraded to 2.3.16-2 now and it runs without any flaws, like all the time before. I had no time to investigate this any longer thand 2 hours with 2.3.17 installed as this is a production server and I need the email access. I also did not find anything adressable in the logs.

[root@riot dovecot]# systemctl status dovecot
● dovecot.service - Dovecot IMAP/POP3 email server
   Loaded: loaded (/usr/lib/systemd/system/dovecot.service; enabled; vendor preset: disabled)
   Active: active (running) since Sat 2021-10-30 10:18:11 CEST; 2s ago
     Docs: man:dovecot(1)
           https://doc.dovecot.org/
Process: 32398 ExecStartPre=/usr/libexec/dovecot/prestartscript (code=exited, status=0/SUCCESS)
Main PID: 32452 (dovecot)
   Status: "v2.3.16 (7e2e900c1a) running"
    Tasks: 4 (limit: 99912)
   Memory: 4.4M
   CGroup: /system.slice/dovecot.service
           ├─32452 /usr/sbin/dovecot -F
           ├─32507 dovecot/anvil
           ├─32508 dovecot/log
           └─32513 dovecot/config

Oct 30 10:18:11 riot.<domain>.com systemd[1]: Starting Dovecot IMAP/POP3 email server...
Oct 30 10:18:11 riot.<domain>.com dovecot[32452]: Warning: Corrected permissions for login directory /var/run/dovecot/token-login
Oct 30 10:18:11 riot.<domain>.com dovecot[32452]: master: Warning: Corrected permissions for login directory /var/run/dovecot/token-login
Oct 30 10:18:11 riot.<domain>.com dovecot[32452]: master: Dovecot v2.3.16 (7e2e900c1a) starting up for imap, lmtp, sieve
Oct 30 10:18:11 riot.<domain>.com systemd[1]: Started Dovecot IMAP/POP3 email server.

This is the configuration
# 2.3.16 (7e2e900c1a): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.16 (09c29328)
# OS: Linux 4.18.0-305.19.1.el8_4.x86_64 x86_64 AlmaLinux release 8.4 (Electric Cheetah)
# Hostname: riot.<domain>.com
auth_mechanisms = plain login
auth_verbose = yes
listen = *
mail_gid = vmail
mail_home = /var/vmail/mailboxes/%d/%n
mail_location = maildir:~/mail:LAYOUT=fs
mail_plugins = " quota fts fts_solr"
mail_privileged_group = vmail
mail_uid = vmail
managesieve_notify_capability = mailto
managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext imapsieve vnd.dovecot.imapsieve
namespace inbox {
inbox = yes
location =
mailbox Drafts {
    auto = subscribe
    special_use = \Drafts
}
mailbox Sent {
    auto = subscribe
    special_use = \Sent
}
mailbox Spam {
    auto = subscribe
    special_use = \Junk
}
mailbox Trash {
    auto = subscribe
    special_use = \Trash
}
prefix =
separator = .
type = private
}
passdb {
args = /etc/dovecot/dovecot-sql.conf
driver = sql
}
plugin {
fts = solr
fts_autoindex = yes
fts_solr = url=http://localhost:<solr_port>/solr/dovecot/
imapsieve_mailbox1_before = file:/var/vmail/sieve/global/learn-spam.sieve
imapsieve_mailbox1_causes = COPY
imapsieve_mailbox1_name = Spam
imapsieve_mailbox2_before = file:/var/vmail/sieve/global/learn-ham.sieve
imapsieve_mailbox2_causes = COPY
imapsieve_mailbox2_from = Spam
imapsieve_mailbox2_name = *
quota = maildir:User quota
quota_exceeded_message = User %u is over the storage quota
sieve = file:/var/vmail/sieve/%d/%n/scripts;active=/var/vmail/sieve/%d/%n/active-script.sieve
sieve_before = /var/vmail/sieve/global/spam-global.sieve
sieve_global_extensions = +vnd.dovecot.pipe
sieve_pipe_bin_dir = /usr/bin
sieve_plugins = sieve_imapsieve sieve_extprograms
}
protocols = imap lmtp sieve
service auth {
unix_listener /var/spool/postfix/private/auth {
    group = postfix
    mode = 0660
    user = postfix
}
unix_listener auth-userdb {
    group = vmail
    mode = 0660
    user = vmail
}
}
service imap-login {
inet_listener imap {
    port = 0
}
inet_listener imaps {
    port = 993
}
}
service lmtp {
unix_listener /var/spool/postfix/private/dovecot-lmtp {
    group = postfix
    mode = 0660
    user = postfix
}
user = vmail
}
service managesieve-login {
inet_listener sieve {
    port = 4190
}
}
ssl = required
ssl_ca = </etc/ssl/certs/ca-bundle.crt
ssl_cert = </etc/ssl/certs/<domain>.com_chain.crt
ssl_cipher_list = TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:EECDH+AESGCM:EDH+AESGCM:@SECLEVEL=2
ssl_client_ca_dir = /etc/ssl/certs
ssl_client_ca_file = /etc/ssl/certs/ca-bundle.crt
ssl_dh = # hidden, use -P to show it
ssl_key = # hidden, use -P to show it
ssl_prefer_server_ciphers = yes
userdb {
args = /etc/dovecot/dovecot-sql.conf
driver = sql
}
protocol imap {
imap_idle_notify_interval = 24 mins
mail_max_userip_connections = 20
mail_plugins = " quota fts fts_solr imap_quota imap_sieve"
}
protocol lmtp {
mail_plugins = " quota fts fts_solr sieve"
postmaster_address = postmaster@<domain>.com
}
local_name mail.<domain_3>.com {
ssl_cert = </etc/ssl/certs/<domain_3>.com_chain.crt
ssl_key = # hidden, use -P to show it
}
local_name mail.<domain_2>.net {
ssl_cert = </etc/ssl/certs/<domain_2>.net_chain.crt
ssl_key = # hidden, use -P to show it
}
local_name mail.<domain>.com {
ssl_cert = </etc/ssl/certs/<domain>.com_chain.crt
ssl_key = # hidden, use -P to show it
}