@ÇiğdemYurtseven everything can be a disappointment depending on the angle it’s looked at
Tips, read the manual, what’s the purpuse and how it should be done.
https://www.suunto.com/en-us/Support/Product-support/suunto_race_s/suunto_race_s/widgets/blood-oxygen/
Laying my opened hand on a flat tablet and not moving while taking measurement works nearly 99% of the times for me on my SRS.