qp and Invalid quoted-printable input trailer: '=' not followed by two hex digits

I have a mail (attached) for which dovecot reports:

imap(test): pid=<32688> session=, Error: Mailbox INBOX.test: UID=1: read() failed: read(/var/mail/test/.test/cur/1695887652.M710714P17846.mbox13:2,RS) failed: Invalid quoted-printable input trailer: '=' not followed by two hex digits

and I fail to see why. There is = used at the end of lines as soft-line break.

Also if you delete "przez system Spa=" it works. If you lave it and delete "<br>=" line it also works.

Doesn't seem to be consistent.

Is dovecot too restrictive here?

dovecot 2.3.20 and 2.3.21

Arkadiusz Miśkiewicz, arekm / ( maven.pl | pld-linux.org )