iMac won’t enter Target Display Mode

Currently have a late 2013 iMac running 10.9.5 and a 2020 MacBook Air. I’ve tried everything to get the two connected, but in System Report on the MacBook, the iMac will show as connected. However on the iMac, the MacBook does not show as connected, but it recognizes the cable.

I’ve reset the SMC and NVRAM on both computers. I’ve booted into Safe Mode on both computers too, and the MacBook still doesn’t register on the iMac. I’ve pressed cmd + f2 and fn + cmd + f2 when using standard function keys. The cable is brand new as well.