Time has passed, and you, Firefox-Mozilla, continue to ignore a very serious situation. So, here's what I'll say.
I'll be honest with you. I find the round design so difficult to perceive and impractical in everyday life that it may force me to stop using Firefox. Because the Firefox user interface has always been so characteristic, with its RECTANGULAR design with an appropriate level of rounding. Now it's just a typical cheap “design like everyone else's.” And don't tell me that this is how you “integrate” the Firefox design into today's "leading operating systems" like Windows & Mac (By the way, I have serious questions about the future of Windows). Don't! Just give us the option to configure the LEVEL OF ROUNDING in the settings.
Every time I open Firefox, the rounded tabs kill me. It's unbearably painful, inconvenient, and impractical. Your “new” round design really sticks out from the overall aesthetics of Firefox. Here's my proof: when you open the “Application Menu,” you see two completely different designs.
Your website is even "rectangular", guys! It's rectangular with neat edges, and no one is pointing fingers or complaining about it!
Just give users the option to customize the roundness of the design. Because human psychology and practice tell us that "a rectangle is much more reliable and convenient than a circle."
Thank you for your understanding.