The wiki (only the german version https://wiki.openstreetmap.org/wiki/DE:Key:opening_hours Search for the term "Sommer") and a blog (https://www.netzwolf.info/osm/time_domain/erklaerung.html Search for the term "Unterschiedliche Regelsätze für Sommer und Winter") contains some information about different opening_hours for summer/wintertime. I came up with:

Mar Su[-1]-Oct Su[-1]-1 days: Tu-We,Su 14:00-24:00; Th 14:00-02:00; Fr 14:00-04:00; Oct Su[-1]-Mar Su[-1]-1 days: Tu-Th 14:00-22:00; Fr-Sa 14:00-04:00; Su 14:00-21:00

Hard to say if they define their summer and winter in accordance to the summer/wintertime