I have the same error when I helm install the latest version prometheus-community/kube-prometheus-stack with thanos.io v0.25.2 the thanos-storage-config.yaml as following:
type: s3
config:
bucket: monitoring-thanos-dev-metrics #S3 bucket name
endpoint: s3.ap-southeast-2.amazonaws.com #S3 Regional endpoint
encryptsse: true
Then, the thanos-sidecar, thanos-compactor and thanos-sotre has show this error msg: unmarshal errors:\n line 2: field encryptsse not found in type s3.Config