Just got my first FPV setup and I'm getting terrible range with my Eachine EV100 goggles paired with a TinyHawk 2. I replaced the stock VTX antenna with a Micro AXII RHCP like everyone recommends, but now I lose signal at just 5 meters behind me. Same thing happens in front but with slightly better range. Could this be an antenna polarization mismatch like RHCP on the quad but wrong polarization on goggles? The image quality improved but range got worse somehow.

First check that all antenna connections are secure and properly installed - loose connections can cause exactly what you're describing. Also verify you didn't accidentally get LHCP antennas mixed in somewhere.

This is actually normal when mixing LP and CP antennas - you'll lose some signal strength compared to CP-to-CP setup, but it should still work better than bad alignment with LP on both ends. What antennas are you running on the goggles?

Remember that antennas make the goggles - they're just screens. Even an 800mW+ VTX isn't worth much with a crappy antenna setup. Interestingly, my goggles actually worked better with just ONE good antenna than with both cheap dipoles.