Categorized symbolization does not work on bigint columns in QGIS

[reald]

Describe the bug

Categorized symbolization does not work on bigint columns. Reproduced with spatiallite.

How to Reproduce

1. Add a vector layer (spatialite in this case). Note: Steps to create test database with sample values described below.
2. Go to Properties -> Symbolization -> Categorized. Select bigint column ("id") as value, random colors, then choose classification.

3. Shown values are not bigint and do not match database:

987654321012345 in db seems to be 821493369 here
987654321012346 in db seems to be 821493370 here

4. All bigint values in db are treated as "n/a" and become the same color:

QGIS and OS versions

QGIS-Version	3.10.1-A Coruña	QGIS-Codeversion	ef24c52
Kompiliert gegen Qt	5.9.5	Laufendes Qt	5.9.5
Kompiliert mit GDAL/OGR	2.2.3	Läuft mit GDAL/OGR	2.2.3
Kompiliert mit GEOS	3.6.2-CAPI-1.10.2	Läuft mit GEOS	3.6.2-CAPI-1.10.2 4d2925d6
Kompiliert mit SQLite	3.22.0	Läuft mit SQLite	3.22.0
PostgreSQL-Client-Version	10.10 (Ubuntu 10.10-0ubuntu0.18.04.1)	SpatiaLite-Version	4.3.0a
QWT-Version	6.1.3	QScintilla2-Version	2.10.2
PROJ.4-Version	493
BS-Version	Ubuntu 18.04.3 LTS
Aktive Python-Erweiterungen	QuickOSM; QuickWKT; OnlineRoutingMapper; qfieldsync; pluginbuilder3; MapsPrinter; OSMtools; quick_map_services; SelectWithin; ORStools; mmqgis; db_manager; processing; MetaSearch

Additional context

Create test database:

$>sqlite3 bigint.db
SQLite version 3.22.0 2018-01-22 18:45:57
Enter ".help" for usage hints.
sqlite> CREATE TABLE IF NOT EXISTS test (
...> "id" BIGINT,
...> "value" INT);
sqlite> SELECT load_extension('mod_spatialite.so');
sqlite> SELECT InitSpatialMetaData(1);
1
sqlite> SELECT AddGeometryColumn('test', 'position', 4326, 'LINESTRING', 'XYM');
1
sqlite> INSERT INTO test (id, value, position) VALUES
(987654321012345, 1, ST_GeomFromtext('LINESTRINGM(10.416255 55.3786316 1577093516, 10.516255 55.4786316 157709)', 4326) ),
(987654321012346, 2, ST_GeomFromtext('LINESTRINGM(10.316255 55.3786316 1577093516, 11.216255 56.3786316 157709)', 4326) );

[reald]

Possible workaround: Categorize by "to_string(id)" and not "id".

[elpaso]

@reald how exactly did you add the layer?
Can you paste the provider information?

[elpaso]

@reald nevermind, found the issue (it works with OGR provider btw, the issue is in spatialite provider).