Hi @lwy
Thank you for posting.
I have made a test on my side and it works fine for me.
You can take a try with the expression in Filter Query instead of set variable:

LeaseEndDate le '@{addDays(utcNow(),180,'yyyy-MM-dd')}'


This is my test list

After flow runs, I will receive the email

Hope the content above may help you.
Best Regards
If my solution helps, then please consider Accept it as the solution to help the other members find it more quickly.