A few things may explain your skewed results:I am getting huge differences between SEMRush and Google. One keyword in particular which Google says gets 8,100 monthly searches SEMRUsh is reporting as getting 147 monthly searches.
I tried SEMJRush for the first time in ages today and it was way out for me too. Even for a general idea of what keywords URLs were ranking for it didn't encourage me to visit again any time soon.
I hope those that pay the dosh for a subscription get much more accurate and timely results.