relation/1931093 refers to Biala, but the name should be Samuil: https://en.wikipedia.org/wiki/Samuil_Municipality

OSM relation/2362532 is set as a separate admin boundary level 8 for Korsholm but should be part of admin boundary relation/1855924. Please merge.

According to https://en.wikipedia.org/wiki/Gra%C4%8Danica,_Kosovo The municipality of Gračanica was established in 2008 by the Government of the Republic of Kosovo, out of parts of the municipalities of Lipljan, Kosovo Polje and Pristina.

As the Serbian government has stopped to publish statistics for the region and OSM has the data as Republic of Kosovo, it would be helpful to have the proper administrative boundaries.

relation/3826848 городской округ Евпатория, Evpatoria Raion is incorrect as no Raion but city of significance. It is also dupe with relation/1581042 Евпаторийский городской совет, Evpatoria Municipality which is an older dataset and correct.
relation/3826848 conflicts as admin-level 6 and should be deleted as duplicate.

UK ferries are not recognized in osm.org/directions, resulting in major detour via France (try Guernsey-Dorchester)

Hier fehlt das zur Schule gehörende Schwimmbad. Ein Rechteck in der Breite des Gebäudes inter dem bestehenden schmalen Stück entlag der Zufahrtsstraße in Richtung Celler Straße, in der Tiefe analog zum Innenhof. Eckpunkt ca. 52.27051, 10.50958 (eigene Recherche). Es wäre Klasse, wenn dies als Schwimmbad deklariert würde, da es auch von verschiedenen Vereinen (u.a. DLRG, Eintracht Braunschweig) verwendet wird.
Der Eingang ist da, wo der rote Fußweg eingetragen ist.

Ceuta-Algeciras ferry is not recognized in route calculation (osm.org/directions). As of the special status of Ceuta, I'd appreciate a review.

Ferry-road connection does not work, resulting in strange detours i.e. to Valencia on osm.org/directions

https://en.wikipedia.org/wiki/El_Valle_de_Altomira is missing from admin-level 8 relations.
As per https://osm.wno-edv-service.de/boundaries/ I could deduct that this must be a missing area in admin-level 6 349024 (Cuenca) outer border (West) and admin level 8's: 348868 (Buendía), 342705 (Huete), 345640 (Saceda-Trasierra),344289 (Vellisca), 344287 (Villalba del Rey).