RT4 tries to insert unicode characters into db?

I am trying to create ticket from UI with subject containing characters ‘ääää’ and I get following error:

[critical]: Couldn’t create a ticket: Sisemine viga: Couldn’t execute the query 'INSERT INTO Tickets (SLA, LastUpdated, Status, Queue, LastUpdatedBy, Starts, Subject, Type, Started, Priority, Creator, Due, Resolved, Created) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)'Incorrect string value: ‘\xE4\xE4\xE4\xE4’ for column ‘Subject’ at row 1 (/opt/rt4/sbin/…/lib/RT/Ticket.pm:421)
[15750] [Thu May 4 13:36:10 2017] [error]: Ticket could not be created due to an internal error (/opt/rt4/share/html/Elements/Error:78)

The same happens when I create ticket via sending email to the queue.

The table has utf8 encoding.

I haven’t seen anyone else having this problem which clearly means that I have missed smt. What is it? Have been trying to convert data in the db and changing character sets but nothing helps.