Please be aware of the new STAC schema for datasets that are ingested into the ESA PRR (the project result repository - long term preservation archive for ESA EOP project results).
The new schema regards mostly the metadata at collection level and is described here: https://eoresults.esa.int/prr_collection_specifications.html
The PRR collection editor provides a utility to create STAC metadata along that schema:
https://eoresults.esa.int/prr_collection_editor.html
Further updates regarding the STAC asset level will follow over the next weeks