I was planning on refinancing my home that I purchased at the end of 2020. It's gone from ~$500k to ~$750k since I bought it, but adding an extra 25% ($125k) to

I was planning on refinancing my home that I purchased at the end of 2020. It's gone from ~$500k to ~$750k since I bought it, but adding an extra 25% ($125k) to the mortgage (bringing it from currently $470k to ~$600k) would increase my monthly payments by 50%. It's actually ~$200/m cheaper for me to take out an 8% $125k loan separate from my mortgage than it is to refinance the bulk from 2.75% to 5.2%.