@unfa that box style and font looks exactly like juce-based plugins. I checked locally, do not have that here, so I would say it is not from distrho-ports.
You can do a quick grep to find the culprit.
Just:
$ grep -r "Error opening preset" /usr/lib/{lv2,vst}/
@falktx Thank you!
Interestingly it has pointed me to Matt Tytel's Vital.