To report a bug, you must register at https://bugs.kde.org/ to gain access to the “KDE bug tracking system”, i.e. “KDE’s bug tracker”. Keep in mind that the e-mail address you use there must firstly be existing / valid and secondly that it can be viewed by any visitor to the site. But the likelihood of your address falling into the hands of spammers there seems to be very low, because the address I use I use exclusively for access to the KDE bug tracking system and have not had a single spam mail in my mailbox in the years I have been registered there.
You can read what a bug report should look like under Reporting Bugs in the Krita manual (the input mask looks slightly different today), or the User Guide on KDE.ORG, which I like less. Please use the drop-down menus to select the software, i.e. Krita, the version number, the operating system and try to narrow everything down as much as possible using the drop-down menus available there.
And after completing the bug report, i.e. after you have sent it, please publish the link to the bug report here in this topic.
Michelist