There's something seriously wrong with code pages and perhaps icu. Using dooble-qt6, simply opening it, displaying the release notes and closing it results in this,
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias KS_C_5601-1987 maps to EUC-KR already, but someone is trying to make it map to cp1363
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias KSC_5601 maps to EUC-KR already, but someone is trying to make it map to cp1363
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias 5601 maps to EUC-KR already, but someone is trying to make it map to cp1363
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias windows-949 maps to cp1363 already, but someone is trying to make it map to EUC-KR
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias KS_C_5601-1989 maps to cp1363 already, but someone is trying to make it map to EUC-KR
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias csKSC56011987 maps to cp1363 already, but someone is trying to make it map to EUC-KR
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias korean maps to cp1363 already, but someone is trying to make it map to EUC-KR
[107:19:0511/115608.818000:ERROR:text_encoding_registry.cc(139)] alias iso-ir-149 maps to cp1363 already, but someone is trying to make it map to EUC-KR
As far as I can see, the release notes are straight ASCII.
I've also seen errors related to ICU.
For Mozilla, had to re-add cp850 at one point when they cleaned up the codepage section.
Doing the same with dooble-qt5 results in no messages to stdout/stderr
Another observation is here, going to github often sees dooble-qt6 close pretty quick. Redirecting stdout/stderr (dooble 2>&1 | tee dooble.log) sees dooble display the pages. Timing issue I assume.