It happened three times so far, and not successively, rather randomly. After the end of my sleep, i noticed my recorded resting heart rate which was 38bpm, 39bpm and 37bpm respectively, but after a few hours later the watch had recorded wrong numbers (42,42 and 43 respectively) changing obviously and the result of the average RHR. Those numbers were the initial values before the beginning of my sleep. The minimum heart rate was 36bpm in these 3 cases.
Usually, after a 7 hour sleep, my daily resting heart rate is between 37-39bpm.
Update 5/4/2023: It happened again 4th time. When I tried to load the data from the watch to the app connect, the RHR 38bpm was transformed to 43bpm (in the watch) and loaded as such (43bpm) to the app.