Failure of Success Criterion Question for F30 and F38

Hi,

I'm reaching out since my organization has been working on updating our
policies to be fully AODA compliant and accessible for all audiences.

The success criterion around images has been rather specific and on our end
and we wanted to get some clarification.

F30:
https://www.w3.org/WAI/WCAG21/Techniques/failures/F30
Would it be considered a failure for this success criteria if alt text was
present (describing the image to help search crawlers better understand the
image), but the image is considered decorative and hidden
(role="presentation", or aria-hidden="true" for screen readers)?

Alt text is typically used to help us better optimize our pages and content
for search engines and by stripping it out completely across the majority
of images being decorative could have a significant impact on our
visibility overall.

F38:
https://www.w3.org/WAI/WCAG21/Techniques/failures/F38
In this criteria, only role="presentation" is identified as being the
success criteria to mark up decorative images with to hide it from
assistive technology.

Are other methods to (such as aria-hidden="true") valid for this criterion,
or do we HAVE to use role="presentation" solely? We've tested
*aria-hidden="true"* with multiple auditing tools and no issues were
detected, but if the success criteria is taken literally, only
role="presentation" is acceptable?

Thanks in advance!