It kills range. It's workable, but signal quality suffers. I've set up wifi networks that host 100+ phones. Separation of the channels is important. I've seen two APs jam each other. Unplugging the ESP32 device added 20 dB to my signal. quality.
It doesn't affect signal quality. Two devices can transmit on the same frequency and that's exactly what one AP and multiple STAs do all day every day.
APs shouldn't be "jamming each other" and if they are then they are very poor quality units. People run separate APs on the same channel in dense areas all the time.
You don't lose 20dB by plugging in a second AP.
If you insist on separating your AP and STA, you essentially need two radios and any basic WiFi device like an ESP32 will just not have that.