This medium sized ichneumon wasp female (Ichneumonidae sp.) had possibly found a nest of her host in a bamboo stem. Through the cracks in the side of the stem she tried to reach it with her ovipositor.
Possibly it is a Cryptinae but that cannot be determined for sure based on the the photographs.
The wasp referenced in the article of Pieter van Breugel in edition 25 of Hymenovaria  gave me flashbacks to the specimen in this observation. And for sure the observation on waarneming.nl has indeed been approved. I tried to use the Hoplocryptus key [SCHWARZ, 2007]  as well but unfortunately especially the facial details are not visible in the photo’s.
Last season (2022) another female was active in the garden as well.
References1 Nederlands Soortenregister
2 Breugel van, P., (2022). Hoplocryptus confector (Gravenhorst, 1829) (Ichneumonidae: Cryptinae). Hymenovaria, 25, 32-34, https://www.hymenovaria.nl/category/publicaties/hymenovaria/
3 Schwarz, Martin. (2007). Revision der westpaläarktischen Arten der Gattung Hoplocryptus THOMSON (Hymenoptera, Ichneumonidae). Linzer Biologische Beiträge. 39.