@Pien Derkx​ You can set the spark sql formatter to LEGACY and try your steps. Below is what worked for me.

spark.conf.set("spark.sql.legacy.timeParserPolicy", "LEGACY")
 
df.withColumn("date_expected", to_date(col("dateinput", "uwwyyyy")).show()

dateinput -> 3312023

Output came for dateexected -> 2023-03-29

Please try and let me know if this works.