Hey, Sorry for the inconvenience. As a temporary fix you can disable the proton design which is responsible for the new look of tabs or use a theme of your preference. Attaching a support article below for detailed steps on this. https://support.mozilla.org/en-US/questions/1338074#answer-1416867

Hi, This option is no longer available in FF95. Please provide a setting for this so we ALL can continue using FF without major irritation moments. Until then, using Edge (this was probably inspired by M$ infiltrators to determine users to make this move anyway, so now they succeded with me).