I use a 8x8 square glass pan for brownies at 350 for 30 minutes, never used a metal pan for them

Glass is an insulator and metal is a conductor, but there's some sense that the bottom of a pie will bake better in clear glass than in anything opaque, as if some visible, or more likely IR, light is a component. Glass is also thicker. So yeah, it could be the dish, or not. It could be a variation i; the atmosphere, A new thing in your oven, a change in an ingredient, etc. try the metal pan again and see what happens. :D

I always use glass for brownies, too, because I always have...

Same here - I use a Pyrex square baking dish, or oblong, for brownies and lots of other baked items as well. I seem to recall some of my cookbooks advising that pyrex can make things bake faster or brown more easily, and that oven temperatures may need lowering.

My oven is electric and I keep a thermometer in there to make sure the temperature's correct. All other things being equal, perhaps your oven needs recalibrating?

Yup, I learned that when using glass, lower the temp and extend the time.

Here are a bunch of discussions.

https://www.google.com/search?client=firefox-b-1-d&q=glass+vs+metal+baking+pans

I always use a metal pan when making my brownies :-)

I haven't made brownies for decades, but when I did, I only remember making them in metal pans, either 8x8 or 9x13.

During the pandemic, the only bread pan I could find in Palm Springs was Pyrex, and so I bought it for making bread, but then I ordered another Pullman pan so that I could have one at both houses. I still use the Pyrex bread pan when I am not making pain de mie. I judge whether the bread is done by inserting an instant read thermometer, and I don't remember whether it took longer in Pyrex or not. I think it may have, but I did not change the oven temperature.