ChangePoint detection for not daily data

[HiromasaYamanishi]

My data consists of records taken every 20 seconds, as shown below. However, when I performed change point detection with the following parameters, I was able to detect change points, but as shown in the attached figure, the trend line ended up being straight. I've read through the documentation but haven't been able to resolve this issue. I would appreciate it if you could help me.

data
beh_time | count
2023-01-01 10:01:20 | 50
2023-01-01 10:01:40 | 47
2023-01-01 10:02:00 | 46
2023-01-01 10:02:20 | 48
2023-01-01 10:02:40 | 52
....

parameter
res = model.find_trend_changepoints(
df=df,
time_col="beh_time", # time column name
value_col="count",
actual_changepoint_min_distance=timedelta(seconds=300),
resample_freq=timedelta(seconds=20),
regularization_strength=0.1,)

result