@MonikaWheat88 Did you ever figure this out? I have spent a while diagnosing this here at the Esri forums as well as MS PowerAutomate forums. I'm not saying this your exact problem, but here's an observation I had. I had a flow working perfectly fine, I hadn't modified save for a few things in the message being put into the Teams channel.
The error is misleading (well at least in this case) as it lead me to believe that the input from the Fetch Updates step based on the same error you received:
The execution of template action 'Apply_to_each_2' failed: the result of the evaluation of 'foreach' expression '@{outputs('Fetch_updates,_changes,_or_deletions_from_feature_layer')?['body/items']}@{body('Fetch_updates,_changes,_or_deletions_from_feature_layer')}' is of type 'String'. The result must be a valid array.
So I went back to my Team channel and looked for the last valid response to make it through. I then attempted to reformat the message output in PA and then the flow suddenly started working again. I don't have an exact before and after but I cleaned some things up and added spaces between each insert parameter in the message. I also didn't change out any of the parameters, like i kept the same editor tracking fields I wanted to see in the message.
This is a complete mystery to me, and since looking at your screen shots, it appears what I have discovered may not help you at all. But there are numerous, unsolved posts about this!
This was a false positive. It now appears that there is no discernable correlation between success & failure.
@SarahRijneke I reviewed your post as well; i'm trying a mix of edits/updates: add new text to string field, modify text in a string field, change the attributed on a coded domain field etc. No pattern has arisen yet.
EDIT!: The same flow which I modified and had working fine immediately failed the second time using the exact same test (change to a record).
@AnthonyLatiniHave you seen this thread yet?