Recently we had a scenario where we were creating a new record through Power Automate step of say Entity A. We started getting error for the field length being less than the input character. So being production instance we moved the patch of the managed solution from dev to Production increasing the length of the field.
Inspite of moving the updated length of the field we were still getting the same old length error in the Create step in Power Automate.
We found that we had to just bring the Power Automate again from the dev instance to the Production instance.
One more possible way can be just to edit the flow and reactivate it in the environment where it is not working.(As my issue was fixed by moving the Power Automate I was not able to try this part, but you can try this if moving power automate from dev to production is not feasible for you.)
So next time if anyone faces such problem with the field length update in D365 not working in Power Automate even after moving the solution then you can keep the above approached in mind.
Hope this helps and saves your time !
D365 CRM Topics by Sid 