SUMMARY

In Wayland browsing files with dolphin. I have a perf trace binary file that may be the cause of it.
 
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/lib/x86_64-linux-gnu/libexec/baloorunner'.
Program terminated with signal SIGABRT, Aborted.
#0  __GI_raise (sig=<optimized out>) at ../sysdeps/unix/sysv/linux/raise.c:50Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `/usr/lib/x86_64-linux-gnu/libexec/baloorunner'.
Program terminated with signal SIGABRT, Aborted.
#0  __GI_raise (sig=<optimized out>) at ../sysdeps/unix/sysv/linux/raise.c:50

[...]

Thread 1 (Thread 0x7f884e732300 (LWP 291743)):
[KCrash Handler]
#3  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#4  0x00007f88529bd859 in __GI_abort () at abort.c:79
#5  0x00007f8850d52a83 in mdb_assert_fail (env=0x55b9dd3191f0, expr_txt=expr_txt@entry=0x7f8850d55270 "IS_BRANCH(mc->mc_pg[mc->mc_top])", func=func@entry=0x7f8850d558f0 <__func__.8022> "mdb_cursor_sibling", line=line@entry=5837, file=0x7f8850d55010 "mdb.c") at mdb.c:1542
#6  0x00007f8850d47a27 in mdb_cursor_sibling (mc=mc@entry=0x55b9dd2cbca0, move_right=move_right@entry=1) at mdb.c:5403
#7  0x00007f8850d49c0d in mdb_cursor_set (mc=mc@entry=0x55b9dd2cbca0, key=0x7ffc06777840, data=data@entry=0x7ffc06777850, op=MDB_SET_RANGE, exactp=0x0) at mdb.c:6151
#8  0x00007f8850d48191 in mdb_cursor_get (mc=0x55b9dd2cbca0, key=<optimized out>, data=0x7ffc06777850, op=<optimized out>) at mdb.c:6372
#9  0x00007f88527ad2de in Baloo::PostingDB::iter<Baloo::PostingDB::prefixIter(const QByteArray&)::<lambda(const QByteArray&)> >(const QByteArray &, Baloo::PostingDB::<lambda(const QByteArray&)>) (this=0x7ffc06777940, prefix=..., validate=...) at /home/mca/kde/src/baloo/src/engine/postingdb.cpp:217
#10 0x00007f88527ac8e6 in Baloo::PostingDB::prefixIter (this=0x7ffc06777940, prefix=...) at /home/mca/kde/src/baloo/src/engine/postingdb.cpp:246
#11 0x00007f88527b4ab9 in Baloo::Transaction::postingIterator (this=0x7ffc06777e10, query=...) at /home/mca/kde/src/baloo/src/engine/transaction.cpp:311
#12 0x00007f885458b18c in Baloo::SearchStore::constructQuery (this=0x7ffc06777e98, tr=0x7ffc06777e10, term=...) at /home/mca/kde/src/baloo/src/lib/searchstore.cpp:318
#13 0x00007f885458a40b in Baloo::SearchStore::constructQuery (this=0x7ffc06777e98, tr=0x7ffc06777e10, term=...) at /home/mca/kde/src/baloo/src/lib/searchstore.cpp:191
#14 0x00007f885458b035 in Baloo::SearchStore::constructQuery (this=0x7ffc06777e98, tr=0x7ffc06777e10, term=...) at /home/mca/kde/src/baloo/src/lib/searchstore.cpp:300
#15 0x00007f885458a40b in Baloo::SearchStore::constructQuery (this=0x7ffc06777e98, tr=0x7ffc06777e10, term=...) at /home/mca/kde/src/baloo/src/lib/searchstore.cpp:191
#16 0x00007f8854589cee in Baloo::SearchStore::exec (this=0x7ffc06777e98, term=..., offset=0, limit=10, sortResults=true) at /home/mca/kde/src/baloo/src/lib/searchstore.cpp:116



SOFTWARE/OS VERSIONSOperating System: KDE neon Unstable Edition
KDE Plasma Version: 5.23.80
KDE Frameworks Version: 5.89.0
Qt Version: 5.15.3
Kernel Version: 5.11.0-40-generic (64-bit)
Graphics Platform: Wayland
Processors: 4 × Intel® Core™ i5-6200U CPU @ 2.30GHz
Memory: 19,0 Gio of RAM
Graphics Processor: Mesa Intel® HD Graphics 520


Seems close to https://bugs.kde.org/show_bug.cgi?id=386266 but not sharing the same stack trace.