[Koha] HTML coding

[erlanda_simonyan at flib.sci.am]

Dear List,
we are using Koha 21.05.
For the fields 504, 520, 563 we are using HTML coding.
In the "Normal view" html tags are seen, which is not normal, but in the ISBD view HTML tags are suppressed and the display of the records is normal.
Is this a bug?
How can we correct the display?
For more details on HTML display, please see:  https://vmc.sci.am/cgi-bin/koha/opac-detail.pl?biblionumber=165 

                                               https://vmc.sci.am/cgi-bin/koha/opac-ISBDdetail.pl?biblionumber=165
Thanks in advance, 
Erlanda