Why is it asking my to pay thousands in Canadian tax if I am a Canadian citizen non-resident living in the UK, and I already paid thousands in UK tax? Is there no treaty?

I lived in the UK for all of 2023 as a non-resident of Canada. I am still a Canadian citizen. I work and live in the UK, and paid my UK taxes as I am self-employed in the UK. Now when I try to file my Canadian taxes with turbotax, it is asking me to pay over $4000 in Canadian taxes on top of the $12000 I already paid and am declaring for my British taxes. Surely this can't be right?