What should I pay attention to when testing if I change the DefaultMode?

[karuakun]

We have confirmed that switching the DefaultMode in the Issue at the following URL improves the situation.
Thanks.
#3678 (comment)

I am still using 3.7.400 and would like to test if setting this value changes the existing behavior.
What points should I keep in mind when conducting the test?

I have checked the following document, and while I can see what values are set when set to standard, I cannot see how this changes from the 3.7.400 default and how it affects existing code.
https://docs.aws.amazon.com/sdkref/latest/guide/feature-smart-config-defaults.html

[dscpinheiro]

The Standard mode is the recommended value (and our default in V4), but the workaround I mentioned in the issue can only be used locally (and not impact deployed applications).

If you do decide to change it, the biggest differences are:

• STS defaults to regional endpoints (instead of the global endpoint)
• S3 requests to the us-east-1 region will use s3.us-east-1.amazonaws.com instead of s3.amazonaws.com