Have you done the math on it though? Yeah, a mortgage stays constant, but to get a mortgage, you need a down payment, closing costs, and whatever you're paying your real estate agent. And then there's maintenance costs, utilities (most purchasable homes are larger than what you'd otherwise rent), probably extra costs to get around, etc.

If you instead took that down-payment and additional costs and invested it in a diversified stock portfolio, how would they compare?

I'm in a similar boat where my mortgage is now less than half of what rent would be, but my house is growing in value far slower than stocks. Here's a nerdy video discussing rent vs buy, and the result is that it's more of a wash than most people assume. This is extra true if you properly account for repair costs (i.e. if you DIY, what's the value of your time?). The decision to rent vs buy is far less consequential in terms of long-term financial impact than most people assume.

Is it fixed? although interest rates are likely to go down so even a non fixed is helpful currently.